INTERNAL THALES ALENIA SPACEemits.sso.esa.int/emits-doc/OHBSYS/MTG/MTG-Generic-ADs/... · 2011-04-12 · The Contingency factors to be applied at all levels (equipment/instrument,

INTERNAL THALES ALENIA SPACEREFERENCE :

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TABLE OF CONTENTS

1. INTRODUCTION..................................................................................................................................................6

1.1 Scope..........................................................................................................................................................6

2. DOCUMENTATION .............................................................................................................................................6

2.1 Applicable documents ..............................................................................................................................6

2.2 Reference documents...............................................................................................................................6

3. GENERAL BUDGET REQUIREMENTS .............................................................................................................7

4. MASS AND MASS PROPERTIES ......................................................................................................................8

4.1 Dry mass ....................................................................................................................................................84.1.1 Prediction ................................................................................................................................................84.1.2 Piloting ....................................................................................................................................................9

4.2 Centering and Inertia ................................................................................................................................9

5. PROPELLANT...................................................................................................................................................14

6. POWER/ENERGY AND BATTERY ..................................................................................................................16

6.1 Introduction..............................................................................................................................................16

6.2 Applicable requirements discussion ....................................................................................................176.2.1 Power Budget Margins..........................................................................................................................176.2.2 Battery...................................................................................................................................................186.2.3 Solar array sizing ..................................................................................................................................18

6.3 Definitions ................................................................................................................................................19

6.4 Average Power.........................................................................................................................................19

6.5 Peak Power ..............................................................................................................................................19

6.6 Maximum Steady State Power ...............................................................................................................196.6.1 Power Budget........................................................................................................................................196.6.2 Energy Budget ......................................................................................................................................206.6.3 Consumption .........................................................................................................................................206.6.4 Current calculations ..............................................................................................................................206.6.5 Dissipation.............................................................................................................................................20

6.7 System Power budget.............................................................................................................................226.7.1 Power Budget........................................................................................................................................226.7.2 Energy Budget ......................................................................................................................................226.7.3 Modes/Phases ......................................................................................................................................226.7.4 Thermal system electrical budget .........................................................................................................23


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6.8 Power Budget Inputs ..............................................................................................................................236.8.1 Inputs to System budget .......................................................................................................................236.8.2 Inputs to Platform Budget .....................................................................................................................23

6.9 POWER & ENERGY BUDGETS ..............................................................................................................246.9.1 Power & Energy budgets management ................................................................................................24

7. EMC ...................................................................................................................................................................25

8. HEAT GENERATION AND DISSIPATION .......................................................................................................26

8.1 Budgets at satellite level ........................................................................................................................26

8.2 Heating power budgets at module level ...............................................................................................268.2.1 Heating power budgets in cold cases ...................................................................................................278.2.2 Heating power budgets in hot cases.....................................................................................................28

8.3 Dissipation budgets at module level .....................................................................................................29

9. SOFTWARE AND MEMORY ............................................................................................................................31

10. RFC................................................................................................................................................................31

11. TREND ANALYSIS .......................................................................................................................................32

11.1 Trend Over Equipment production........................................................................................................32

11.2 Trend from equipment to spacecraft AIT..............................................................................................32

ANNEX 1 TEMPLATE OF POWER BUDGET...........................................................................................................33

ANNEX 2 TEMPLATE OF ENERGY BUDGET ........................................................................................................34


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1. INTRODUCTION

1.1 Scope

This document presents the proposed methodology for the establishment of the satellite engineering budgets.

Satellite performance budgets are addressed in SY-4I for MTG-I and SY-4S for MTG-S.

All critical budget parameters which require system level visibility and control are identified in this document. Foreach of the identified parameter, the following characteristics are defined:

The Margins terminology (e.g. the meaning of “basic”, “current”, “specified” etc....),

The budget methodology (summation rules, statistics, etc.),

The Contingency factors to be applied at all levels (equipment/instrument, sub-system, element, satellite)as a function of the design maturity,

The reporting system that will be used, during the all lifetime of the project, to provide visibility on the statusof each parameter.

2. DOCUMENTATION

2.1 Applicable documents

2.2 Reference documents

MTG Negotiations 09/07/2010 MTG.ESA.SY.MN.0643


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3. GENERAL BUDGET REQUIREMENTS

# Reference

The satellite(s) budgets shall clearly identify the levels of margins.Parents AD-03: [SA-BUD-110]

#

# Reference

Where applicable, budgets shall be derived for beginning and end of life performances, stowed and deployedconfigurations.Parents AD-03: [SA-BUD-130]

#


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4. MASS AND MASS PROPERTIES

The management of the masses is based on two processes:

the prediction (analytical budget) implemented during all the design phase. This prediction is strengthened(essentially by weighing) during phases of production and integration.

The piloting allowing to make sure all the time that the prediction stays in compliance with the assignedobjectives.

The mass budget contributors are:

The satellite dry mass computed thanks to linear sums of mass estimations of different elements includingrelevant margins

The propellant mass of which assessment depends on satellite parameters estimation (dry mass, thrustersefficiency, Isp) as well as delta-V estimation (orbit acquisition, station keeping...).

4.1 Dry mass

4.1.1 Prediction

The prediction of the mass is performed with the following requirements extracted from AD-03 which apply to thedry mass budget:

# AD-03: [SA-BUD-220]

The following additional maturity mass margin factors shall be applied for each satellite unit to account for thehardware development status.a. Completely new development: 20 %b. New development derived from existing hardware: 15 %c. Existing unit requiring minor / medium modification: 10 %d. Existing unit: 3 %.

#

# AD-03: [SA-BUD-230]

A 10% system margin shall be added for the dry mass to the total satellite mass budget until the satellitepreliminary design review (PDR).

#

Once the preceding rules have been applied to each equipment of the satellite, two dry mass estimations areperformed:

Nominal dry mass

Maximal dry mass including maturity margin.

The 10% system margin applied to the maximal mass as required by SA-BUD-230 leads to the system dry mass.

The propellant mass computation is based on:

Nominal dry mass

Maximal dry mass

System dry mass.


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4.1.2 Piloting

The progressive consolidation of the predictions is done with the weighting of the hardware. This consolidation isperformed with the following requirements extracted from [AD-35C], MTDRS which apply to the dry mass budget:

# Reference [MTG-SAT-MTDRS-REQ-0840]

The actual mass of all units intended for Qualification, Flight and Flight Spare(s) shall not deviate from the nominalvalue by more than:

0.5 % for masses > 20 kg

0.1 kg for masses > 10 kg and < 20 kg

1 % for masses > 1 kg and < 10 kg

10 g for masses < 1 kg.

#


The masses shall be measured with an accuracy of:

± 0.1 % for masses > 50 kg

± 0.05 % for masses > 10 kg and < 50 kg

± 1 g for masses > 0 kg and < 10 kg.

#

The dispersions are quadratically added at equipment level and at subsystem level.

The uncertainties are arithmetically added at equipment level and at subsystem level.

Engineering budget relative to dry mass data shall be delivered according to [AD-47C], MTG Requirements forpreparing ICDs and IDS.

4.2 Centering and Inertia

Centering and inertia budgets are elaborated on the basis of the nominal and maximal masses of each componentof the spacecraft, meaning that the 10% system margin on spacecraft dry mass is not considered in this case.

Centering and inertia budgets are part of the justification file (as system requirement verification) and are part of thedefinition file (as budget report).

Centering and inertia budgets shall be elaborated by the mechanical architect in order to verify the following topicsall along the program.


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MASS PROPERTIES VERIFICATION MAIN USER OF THE DATAAccording User’s Manual :

Centering in plane Alignment between geometrical and

inertia axes

Launcher Interface Engineer

According UPS subsystem: thrusters which can be aligned Range of positioning / alignment

Mechanical Architect

According AIT : for MGSE definition duringtransport, hoisting, support phases:

Minimal Zcdg Maximal in plan offset

Structure Responsible

According User’s Manual : Relationship (Msatellite / Zcdg) for

structure qualificationMechanical Analysis Engineer

According AOCS data bank: In-plane centering Maximum product inertia Maximum main inertia

These data are computed during orbital life

System Engineer

Engineering budgets relative to mass properties data shall be delivered according to [AD-47C], MTG Requirementsfor preparing ICDs and IDS.

For system SRR, system/satellite PDR and satellite CDR, the mass and properties budget shall be composed ofthe following data (TBC) :

o LAUNCH : Launch launch data with gravity along –Zo BOT : Beginning of Transfer Solar Arrays partially deployed, Antennas not deployed

Gravity along –Z due to main engine activationo EOT : End of Transfer Same than BOT but with ~2/3 of propellant consumedo BOL : Beginning of Life Solar Arrays, antennas and baffles covers are totally deployed with

0g.o BOL SKM -Y : Ergol are pushed along –Y direction inside the tankso BOL SKM +Y : Ergol are pushed along +Y direction inside the tankso BOL SKM -X : Ergol are pushed along –X direction inside the tankso BOL SKM +X : Ergol are pushed along +X direction inside the tankso EOL : End of life Most of the ergol are consumed with 0g.o EOL SKM -Y : Ergol are pushed along –Y direction inside the tankso EOL SKM +Y : Ergol are pushed along +Y direction inside the tankso EOL SKM -X : Ergol are pushed along –X direction inside the tankso EOL SKM +X : Ergol are pushed along +X direction inside the tanks

Before Mass and Properties tests, the predicted budgets shall take into account the AIT configuration inaccordance with AIT team (non-flight items, missing elements, Archimedes push effect, …). This mass andproperties prediction shall be available after the satellite CDR and shall be updated in accordance with weighedmass availability.

The Mass and Properties budget for flight shall be derived from correlated data after Mass and Properties test.


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Centering shall be computed, measured according to the five following requirements of section 4.4.2 of [AD-35C],MTDRS.


The locations of the centre of mass of each unit, with tolerances, shall be given in the unit ICD, based on bothnominal and maximal masse.

#

# Reference [MTG-SAT-MTDRS-REQ-xxxx]

Deleted

#


For deployable units (Solar Array, antenna,...), calculated location of the centre of mass shall be given for each in-orbit configuration in S/C coordinates system.

#


The location of the centre of mass for equipment intended for Qualification, Flight and Flight Spare(s) shall notdeviate from the nominal location by more than 2.0 mm radius sphere.

#


The centre of mass location shall be measured with an accuracy of 0.5 mm.

#

Moment of inertia shall be computed, measured according to the seven following requirements of section 4.4.3 of[AD-35C], MTDRS.


Nominal and maximal moments and products of inertia of each unit, with tolerances, shall be recorded in the unitICD.

#


For deployable units (Solar Array, antenna,...), calculated inertia values shall be given for each in-orbitconfiguration in S/C coordinates system.

#


The value of the moments of inertia of equipment intended for Qualification, Flight and Flight Spare(s) shall notdeviate from the nominal value by more than 10% except for equipment having a moment of inertia lower than 0.1kg.m².

#


Calculated values only shall be supplied for equipment having a moment of inertia lower than 0.1 kg.m².


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#


The moments of inertia shall be measured with an accuracy of ± 5%.

#


Deleted

#


Inertia and products of inertia shall be defined according to the following convention:

Ixx = mi [(yi-yG)²+(zi-zG)²]

Ixy = [mi (xi-xG)(yi-yG)]

where mi is one elementary mass (which has xi, yi and zi as co-ordinates) of the unit which has xG, yG and zG ascoordinates for its centre of gravity.

#

In addition to this standard convention, the full computation of the mass and properties computation from theequipment j of a sub-system i to the satellite can be summarized as follows :


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Computation of :Mi = sum (Mij)X CoG i = sum (Mij x Xij) / Mi

Y CoG i = sum (Mij x Yij) / Mi

Z CoG i = sum (Mij x Zij) / Mi

Computation of :Msat = sum (Mi)X CoG sat = sum (Mi x Xi) / Msat

Y CoG sat = sum (Mi x Yi) / Msat

Z CoG sat = sum (Mi x Zi) / Msat

For all equipment j= 1 to Neq of sub-system n°i For all sub-system i=1 to Nss of satellite For satellite

Computation of Equipment Mass Properties at SSCoG in Rsat

I'xx ij = Ixx ij + Mij x ((Yij - Ycdgi)² + (Zij - Zcdgi)²)I'yy ij = Iyy ij + Mij x ((Xij - Xcdgi)² + (Zij - Zcdgi)²)I'zz ij = Izz ij + Mij x ((Xij - Xcdgi)² + (Yij - Ycdgi)²)P'xy ij = Pxy ij + Mij x (Xij - Xcdgi) x (Yij - Ycdgi)P'yz ij = Pyz ij + Mij x (Yij - Ycdgi) x (Zij - Zcdgi)P'zx ij = Pzx ij + Mij x (Zij - Zcdgi) x (Xij - Xcdgi)

Computation of Sub-System Mass Properties atSS CoG in Rsat

Ixx i = sum (I'xx ij)Iyy i = sum (I'yy ij)Izz i = sum (I'zz ij)Pxy i = sum (P'xy ij)Pyz i = sum (P'yz ij)Pzx i = sum (P'zx ij)

Computation of Sub-System Mass Properties atSAT CoG in Rsat

I'xx i = Ixx i + Mi x ((Yi - Ysat)² + (Zi - Zsat)²)I'yy i = Iyy i + Mi x ((Xi - Xsat)² + (Zi - Zsat)²)I'zz i = Izz i + Mi x ((Xi - Xsat)² + (Yi - Ysat)²)P'xy i = Pxy i + Mi x (Xi - Xsat) x (Yi - Ysat)P'yz i = Pyz i + Mi x (Yi - Ysat) x (Zi - Zsat)P'zx i = Pzx i + Mi x (Zi - Zsat) x (Xi - Xsat)

Computation of Satellite MassProperties at Sat CoG in Rsat

Ixx = sum (I'xx i)Iyy = sum (I'yy i)Izz = sum (I'zz i)Pxy = sum (P'xy i)Pyz = sum (P'yz i)Pzx = sum (P'zx i)

Inputs:MassCoG wrt RsatEquipement Inertia at Equip.CoG in SS local axes //Rsat

MijXij, Yij, ZijIxx ij, Iyy ij, Izz ijPxy ij, Pxz ij, Pzx ij


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5. PROPELLANT

The propellant mass estimation depends on:

The delta-V estimation of each manoeuvre

The Isp estimation of each manœuvre

The estimation of the efficiency of the manœuvre realisation

The dry mass of the satellite (nominal, maximal and system dry masses).

The orbit acquisition and orbit control delta-V are estimated following the applicable SRD requirements, i.e.:

# AD-03: [SA-BUD-410]

The propellant budgeting shall, as a minimum, include the following manoeuvres:a. All the manoeuvres from launch until acquisition of the GEO orbital location;b. All the manoeuvres necessary to maintain the orbit parameters within the required conditions (e.g.

manoeuvres to control longitudes and inclination);c. All the manoeuvres necessary to maintain the optimal attitude of the satellite (e.g. wheel off- loading, yaw-flip)d. All manoeuvres necessary to maintain the collocation of the satellites;e. Ten emergency sun acquisition/recovery (e.g. due to safe mode assuming a duration of 48 hrs);f. The required capability for relocation manoeuvres (4 orbital relocations);g. The final transfer into graveyard orbit at EOL;

#

# AD-03: [SA-BUD-420]

The propellant budget shall assume the worst case launcher injection inaccuracy (at 3 sigma).

#

# AD-03: [SA-BUD-430]

The propellant budget shall assume worst case (3 sigma where appropriate) of the following errors:a. Thruster misalignmentb. Thruster efficiencyc. Propellant loadingd. Propellant residualse. Mixture ratio shiftf. Inaccuracy of the employed propellant gauging method.

#

# AD-03: [SA-BUD-440]

The worst case launch date (between 2016 and 2030) and time shall be considered for the derivation of thepropellant budget.

#

# AD-03: [SA-LTM-010], [SA-LTM-020]

The MTG satellites shall be designed for a nominal in-orbit lifetime of 8.5 years following a maximum on-groundstorage of 10 years (under conditions to be specified by the Contractor).

#


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The delta-V associated to the AOCS needs (reaction wheels unloading and emergency Sun acquisition/recovery)have also to be considered.

All the errors are accounted for in the Dispersion correction term, and the propellant mass is computed accountingfor specific impulse and thrusters efficiency. Propellant residuals are added to this budget to reflect the fact that thepropellant tanks cannot be fully depleted.


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6. POWER/ENERGY AND BATTERY

6.1 Introduction

The power budget (steady state and peak) sizes the power system while the constant verification of consumptionand power resource capabilities and applied margins will ensure that the power system has enough powerthroughout the mission.

The power budget management is maintained by the relevant satellite Prime. The initial power allocation foreach user drives the solar array and battery sizes. It is highly likely that the power needs of several users willevolve during the program development. Only the Prime Contractor is in the position to be able to determine ifthese changes can be accommodated by margins at level of instrument, platform or a combination. If this is notpossible, then the requested power increase must be re-evaluated and alternatives identified, only as a last resortwould the solar array and/or battery size be changed. The power budget is a “living” budget and will beconstantly updated according to latest design/test information of users consumption, solar array and batteryperformance ensuring that the power budget is always positive and identifying any trends that require attention assoon as possible.

The power budget incorporates margins as specified by ESA to cover unit design maturity (SA-BUD-310), anoverall system margin of 10% of the total load covering SA-POW-140 and SA-BUD-320, and 10% margin for theBattery Charging (SA-POW-150). To avoid unnecessary margin upon margin, the platform and instrumentsuppliers shall provide realistic power Worst Case (and EOL when relevant) values without margins at theirlevel since this is already considered with the application of the maturity margin.

It should be stressed that in order to be a useful tool (not only for checking the sizing of the powerresources but also as an input to test predictions) the power budget shall use realistic values with anymargins or uncertainties clearly identified.

Power Loads(Platform andInstruments)

Battery

Solar Array

PDUPCU

Bus Regulation

LCLs, FCLs,

Heater Switches

BCR BDR

Peak Loads & Margindetermines LCL& FCL Current

Rating

Available S/Apower & time

betweenEclipses &Margin sizes

BCR

Power Load &MarginSizes BDR

Power Load &Margins sizes

Battery

Power Load& Marginssizes Solar

Array

Figure 6-1 Power system elements and impact upon power budget and sizing


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6.2 Applicable requirements discussion

6.2.1 Power Budget Margins

# [AD-03] SA-BUD-310

The following additional maturity power margin factors shall be applied for each satellite unit to account for thehardware development status.a. Completely new developments: 20 %b. New developments derived from existing hardware: 15 %c. Existing units requiring minor / medium modification: 10 %d. Existing units: 5 %.

#

This requirement is applicable at all levels of the power budget. The platform and instrument suppliers shall ensurethat these margins are allocated and reported. The inputs to higher level budgets shall give the net power and theapplied margin as separate items, this will avoid that margin upon margin is applied unnecessarily.

It is considered that the maturity margin shall be applied to the average Beginning of Life power values. Ideally themeasured power consumption on ground should be the same as the power budget considering 0% maturitymargin.

# [AD-03] SA-BUD-320

At least 10% System margin shall be added to the total satellite power and energy budgets until the satellitepreliminary design review (PDR). The system margin is calculated considering (as a minimum) the failures of onesolar array string and one battery cell during all the design life of the power system including all spacecraft modesof operation.

#

Note: Following the satellite PDR reductions in system margins can be proposed (to be agreed by the customer) if justified bythe maturity of the platform, instruments, subsystem and equipment status.

This requirement is applicable only at satellite level and shall be applied only by the Prime. A 10% margin shall beapplied to the sum of all power users (including the resources required to recharge the battery). The resulting grandtotal is to be compared with the power resources (Solar Array and Battery) accounting at least for one failure in thesolar array and one failure in the battery module, or more if required to achieve the desired reliability) to ensure thatthese resources can provide enough power. Clearly the PCDU, SADM and harness shall be designed to be able tocope with the power including all margins. This 10% margin is applied to all mission phases of the program.

# [AD-03] SA-POW-140

The worst case power and energy margins (considering one solar array string loss and one battery cell failed) shallnot be less than 10% during all the design life of the power system including all spacecraft modes of operation.

#

This requirement is applicable only at satellite level and shall be applied only by the Prime. During the developmentof the MTG satellites the unit maturity margins will decrease to zero, (there will be a time in the distant future whereactual hardware will have been manufactured and tested and test results will be available) and the uncertaintiesregarding the Solar Array and Battery performances will have been eliminated. This requirement is complementaryto SA-BUD-320 since the maturity and uncertainty margins will be zero, yet there is still a desire (or in this case arequirement) that the satellite shall exhibit a 10% power margin throughout it’s in-operational lifetime to allow forany unforeseen events that may require additional power (e.g. increase of heating, increase of power ofmechanisms due to wear, need to have both redundancies ON of one or more units....)


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6.2.2 Battery

The following requirement taken from AD-03 applies to the power budget:

# [AD-03] SA-POW-150

The margin for energy recharge shall be no less than 10%, for during all the design life of the power systemincluding all spacecraft modes of operation.

#

This requirement is applicable to the Platform level and shall be managed by the Platform supplier. There are acouple of aspects to this requirement,

1) The reporting of the 10% power margin required to recharge the battery. This can be achieved either byensuring that there is always a 10% power margin from the Power System (Solar Array + PCDU + Losses),or by ensuring that the battery can be recharged from the worst case Depth of Discharge state to a fullycharged state within 90% of the time allocated for battery charging (hence the 10% margin is in terms orrecharge time)

2) The resources for the battery charging have to be dimensioned +10%, this includes the Battery ChargeRegulators, the Battery, the sizing of the harness..... These points do not have to be reported within thepower budgets but shall be part of the design verification.

The reporting of the 10% energy recharge margin shall show the margin philosophy adopted (power or time) andthe margin shall be itemized within the platform power budget.

Figure 6-2 Power budget margin application

6.2.3 Solar array sizing

The power budgets shall clearly indicate the hypothesis used when presenting solar array power. The consideredfailure cases, operating modes – sun aspect angle, degradation factors …. , and margins shall be listed.

maturity margin

SA-BUD-310 power units

unit 1 20% pow 1 + 20%

unit 2 5% pow 2 + 5%

PAYLOADS unit 3 5% pow 3 + 5%

unit 4 10% pow 4 + 10%

unit 5 10% pow 5 + 10%

unit 6 20% pow 6 + 20%

PLATFORM unit 7 10% pow 7 + 10%

unit 8 5% pow 8 + 5%

batt recharge SA-POW-150 +10%

total power load A

system margin SA-BUD-320 B = A + 10% at PDR

EPS achievable pow C

EPS MARGIN SA-POW-140 C-B > 0

See Battery Paragraph


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6.3 Definitions

This chapter provides the definitions for the phrases and words which shall be applied for the MTG program.

6.4 Average Power

From AD-34c

The average power demand shall be defined as the average during a period of 5 minutes shifted to any point intime where this average yields a maximum.

6.5 Peak Power

From AD-34c

Peak power demand shall be defined as the maximum peak of duration less than 2s (TBC) not including in-rushcurrents

6.6 Maximum Steady State Power

The maximum steady state power shall be defined as the maximum power demand exceeding 2 seconds.

`

Wost CasePeak Power

< 2 secs

5 mins

Average Power

Max SteadyState Power

>2secs

Sketch not to scale

Time

Pow

er

6.6.1 Power Budget

In the good old days, the Power Budget was the sum of the average power values of all the electronic units addedto the average power demand of the thermal control subsystem and a few margins were added to give a typicalpower load for all mission phases.


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For MTG it is requested that the power budget considers the peak power values of the electronic units and thepeak power values of the thermal control subsystem (ECSS-E-ST-20C paragraph 5.2.2.2.C). A simplisticapproach would be to add arithmetically all the peak values of all the user consumption but this would provide anunrealistically high power figure.

Therefore a more realistic approach is that the power budget shall consider the maximum steady statepower load + the worst case peak value + margins. The “worst case peak value” can be different for eachsatellite phase, and the power budget shall reflect this. For each mission phase the worst case peak shall bedetailed in terms of description of contributor (e.g. if the worst case peak is caused by thermal control, reactionwheel......) and the amplitude and duration of the peak with respect to the contributors maximum steady state (e.gpeak amplitude is 35W of 1.5 seconds above the maximum steady state of 125W with a frequency of 1Hz). Thisinformation shall be included in the Power Budget. With this information the peak load can be compared with thepower subsystem resources and any peak case that exceeds the EPS resources will have to be analysed on acase by case basis.

6.6.2 Energy Budget

For MTG, the Energy Budget is the sum of all the average consumptions of all the power users + therequired margins. The Energy Budget shall not be limited to the battery but shall provide the average powerdemand for each mission phase.

6.6.3 Consumption

The consumption of a unit (or instrument) is defined as the measured current x the measured voltage, where themeasured voltage shall correspond to the nominal mainbus voltage (50V ± 0.5%), measured at the input connectorof the unit/equipment/instrument.

Using the nominal mainbus voltage for the consumption instead of the minimum/maximum range, will give realisticconsumption values which can be used for a refined harness voltage drop analysis to calculate the harness losses.

6.6.4 Current calculations

There are occasions when it is required that the currents are calculated, from the given consumption valuesexpressed in W, e.g. for the sizing and verification of LCLs, wires, and connector contacts.

For these cases, the current for electronic equipment shall be calculated using the provided consumption in Wdivided by the minimum Voltage specified for the electronics (46V).

For heaters, the current shall be calculated using the provided consumption in W divided by the minimum Voltagespecified for the heaters (48V). If the heater resistance is being used and the current is being calculated (for LCL,wire, contact sizing) then the maximum Voltage (50V) shall be considered.

6.6.5 Dissipation


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Misguided thermal engineers have been known to take the power budget as input to their thermal analysis,(mis)reading power consumption values for dissipation figures. Warning to all misguided thermal engineers, theyare not the same thing for MTG !

For example the dissipation of the PCDU will not be the same as the consumption. There will be a consumption ofthe PCDU electronics and there will be an additional dissipation of the Solar Array Shunts. There will be instrumentunits which receive power from the platform and will provide switched or secondary power to downstream units, inthis case the ensemble of these units will be reported as power consumption, but the dissipation will be distributedover several units.

In the cases that the dissipation is not the same as the consumption, the equipment supplier shall provide details ofthe dissipation in addition to the consumption.

The platform supplier shall provide a dissipation (loss) figure for the harness, initially based upon a simple % lossdepending upon the power load, and finally using the values derived from the harness voltage drop analysis whichshall use the characteristics of the implemented harness.


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6.7 System Power budget

6.7.1 Power Budget

Each satellite Prime shall produce a power budget showing the sizing peak power loads for each mission phase.

The budget shall consider the maximum steady state power load (Pmax steady state) + the worst case peakcondition, where this worst case peak condition is identified and quantified in terms of amplitude, duration andfrequency. If several units have simultaneous peaks then this will be analysed on a case by case basis, either theEPS has adequate resources to handle the peaks or else strategies have to be defined to avoid the excessivepeaks.

All margins shall be clearly identified and itemized separately.

The battery charge and recharge conditions shall be detailed in this budget, identifying the peak power and profilefor battery recharge and peak power demand during the eclipse. The predicted battery Dod shall be provided foreach case where the battery power has been used.

In addition to the mainbus loads, the Power budget shall identify the power provided by the solar array so that apower load versus the energy resources comparison can easily performed.

The template for the Power budget is given in Annex 1 .

6.7.2 Energy Budget

Each satellite Prime shall produce an Energy budget showing the average power loads for each mission phase.


In addition to the mainbus loads the Energy budget shall identify the power provided by the solar array and batteryso that a power load versus the energy resources comparison can easily performed.

The template for the Energy budget is given in Annex 2.

6.7.3 Modes/Phases

The power budgets shall be prepared considering at least the following Modes :

Launch

LEOP

On-station (operational Beginning of Life)

On-station (operational End of Life)

SAFE (Beginning of Life)

SAFE (End of Life)

Decontamination (Beginning of Life)

Decontamination (End of Life)

Yaw Flip (Beginning of Life)


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Yaw Flip (End of Life)

Note that these phases may be redefined during B2 phase

6.7.4 Thermal system electrical budget

The thermal system deserves a dedicated paragraph since experience has shown that the inputs to the systempower from the thermal engineers tend to follow the thermal rules and not the electrical ones.

The thermal budget is typically expressed in W as an average while in reality there will be cycling of the heaterlines where the sum of the peaks will obviously be higher than the average.

For MTG all the thermal systems (platform and instruments) shall provide average power figures, maximumsteady state and peak figures identifying the peak amplitude, duration and frequency for each missionphase.

It is possible that the peak value is very close to the maximum installed heater capability when exiting from a coldcase and the power system will have to provide this abnormally peak power. If this proves to be a driver for thepower system then alternative strategies can be investigated such as incremental heating of different areas tominimise the peak power demand.

The sizing of the thermal control heaters shall take into account the requirement of AD-34c, the voltage at theheater input is a minimum of 48V and a maximum of 50V. All power figures used for the budget shall considerthe nominal bus voltage of 50V.

6.8 Power Budget Inputs

This chapter defines the expected inputs to the power/energy budgets.

6.8.1 Inputs to System budget

The Platform supplier shall provide to the Satellite Prime for each PCDU power line the average, maximum steadystate and peak power load per mode/phase expressed in W.

The payloads suppliers shall provide to the Satellite Prime for each power line, the average, maximum steady stateand peak power load per mode/phase expressed in W. For the peak power values, the amplitude, duration andfrequency shall be provided.


6.8.2 Inputs to Platform Budget

The Satellite Prime Contractors shall provide to the Platform Supplier the power load (average, maximum steadystate and peak) for each power line for each payload. For the peak power values, the amplitude, duration andfrequency shall be provided.This information is initially provided via requirement specifications, then payload ICD, and finally test data. Theintention is to use the most up-to-date and accurate information available for the power budgets.Initially this value can be the allocated power for each payload line, but as the MTG program develops these valuesshall be replaced by improved estimates and measured values.


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6.9 POWER & ENERGY BUDGETS

6.9.1 Power & Energy budgets management

The Satellite Prime Contractors shall be responsible to validate each power value and ensure the correct marginshave been applied.

The Satellite Prime Contractors shall verify that the overall power demands including the applied margins respectsthe power resource capabilities.

The Satellite Prime Contractors shall identify any power consumption trend (increase or decrease) and ensure thatthe projected trend line is compatible with the power resource capabilities and other subsystems, particularly thethermal control subsystem.

A typical flowchart for this reporting and verification process is outlined in the following:

OHB responsibility

MTG PRIMETAS

<

TAS responsibility

<commonality

MTG Project/ MTG TAS electric. organisation.vsd

ESA SRDSA-BUD-310: maturity factor shall be applied for each satellite unit to account for hardwaredevelopment status : [completely new development: 20%] [new development derived from

existing hardware : 15%] [existing units requiring [minor /medium modification: 10%] [existingunits: 5%].SA-BUD-320 : At least 10% System margin shall be added to the total satellite power andenergy budgets until the satellite preliminary design review (PDR). The system margin iscalculated considering (as a minimum) the failures of one solar array string and one battery

cell during all the design life of the power system including all spacecraft modes of operationSA-POW-140 : The worst case power and energy margins (considering one solar array stringloss and one battery cell failed) shall not be less than10% during all the design life of thepower system including all spacecraft modes of operation.SA-POW-150: The system margin for energy recharge shall not be less than10%, during all

the design life of the power system including all spacecraft modes of operation.

EDRSSA-BUD-310: idem SRDSA-BUD-320 and SA-POW-140: The difference between the total power load and the available

power (considering one solar array string loss and one battery cell failed) shall always have apositive margin greater or equal to 10%.SA-POW-150: idem SRD

MTG POWER BUDGETsTASKS/RESPONSILITIES FLOW CHART

MTG-SRDAD-03(TAS)

ECSS ND-09Electrical-Electronic

(ESA)

POWER BUDGET/MARGINSGUIDELINES (TAS)

EDRSSS-2 (TAS)

PLATFORMIRD-I

SA-2PI

PLATFORMURD

SA-2PU

MTG-Isystem

MTG-IPower budget

(TAS)

DCS & GEOSARconsumption

LIconsumption

FCIconsumption

RMUconsumption

MTG-SPower budget

(OHB)

IRSconsumption

UVNconsumption

MTGPLATFORMconsumption

MTG SOLARARRAY BATTERY

& PCU SIZING

>

MTG-I PLATFORMPROCUREMENT

(OHB)

MTG-Ssystem

MTG-SPowerbudgetreport

MTG-SPowerbudgetreport

MTGPowerbudget

synthesis(TAS


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7. EMC

The following requirements are applicable to all levels of the satellite and all levels (unit, subsystem, instrument,satellite).

# [AD-03] SA-EMC-160

A margin of at least 6 dB shall be demonstrated, except for pyrotechnic devices where a minimum margin of 20 dBshall be demonstrated.

#

# [AD-03] SA-EMC-170

If the final demonstration of the margins at satellite level is done by analysis (relying on satellite test results), theuncertainties due to measurement errors and to model inaccuracies shall be taken into account in order to leave atleast a net margin of 6dB (20 dB for pyrotechnics).

#

Note: derived from ECSS-E-ST-20C , [ND12] section 6-6-1-3-b.

The verification of these margins shall be achieved by the EMC control plan, EMC test specifications and EMCanalysis reports. The flowchart for this reporting and verification process for MTG-I is outlined in the followingsketch, this approach is also applicable for MTG-S:

MTG Platform UnitEMC analysis (OHB)

Instrument EMCanalysis (TAS)

MTG-I EMC analysis(TAS)

PDR

MTG-I Unitsmanufacturing

MTG-I Units &S/System test and

reports

MTG-I EMC analysisupdate (TAS)

MTG-I InstrumentUnit EMC analysis

(TAS)

MTG-I instrumentUnit on PlatformEMC analysis(OHB-TAS)

MTG SatelliteEnvironnement

SS-4 (TAS)

MTG EMC & RFCControl PlanSS-9 (TAS)

MTG Electrical DesingRequirement Spec.

SS-2 (TAS)

MTG EMC & RFCspecificationSS-5 (TAS)

MTG-I Unit &S/Syst. Test Resultsanalysis & synthesis

(TAS)

MTG-I PDR

- Satellite & Platform design justif doc. (SA-5)*- DDV Plan (SA-8)*- S/System& Unit Verif. & Test Plans (AV-13)*- Satellite test requirement spec preliminary- Satellite Frequency Plan (SA-10)- EMC/ESD, RFC analysis & report(SA-7)

MTG Units EMCcontrol plan

(MANUFACTURER)

MTG-I Units &S/SystemTest

requirement spec.

MTG-I testrequirementspec.update

(TAS)

CDR

MTG-I CDR

- Satellite Environment & Test specification (SS-4)*- Satellite & Platform design justif doc. (SA-5)*- DDV Plan (SA-8)*- S/System& Unit Verif. & Test Plans (AV-13)*- Satellite test requirement spec update- Satellite Frequency Plan (SA-10)- EMC/ESD, RFC analysis (SA-7)- EMC/ESD, RFC test reports/synthesis (AV-14)*

MTG-I EMC tests(TAS)

MTG Unit suppliersEMC analysis &

inputs


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8. HEAT GENERATION AND DISSIPATION

The following requirements specify the conditions to establish the heat generation and dissipation budgets atsatellite and module levels.

The heating power budget is related to the power generated by the thermal control heaters.

The dissipation budget is related to the dissipative power rejected by the units (electronics, cryo-coolers…).

8.1 Budgets at satellite level

#

The budgets shall be computed by adding arithmetically the contribution of every module.

#

#

The power budgets shall be provided at equinox, winter solstice and for the extreme cases which minimise andmaximise the heating budget.

#

#

The dissipation budgets shall be provided for the same periods than the heating power budgets.

#

#

The budgets shall be provided and updated for each system review as follows:

PDR

CDR

QR

FAR.

#

8.2 Heating power budgets at module level

#

The budgets shall be provided for Beginning Of Life (BOL) and End Of Life (EOL) conditions.

#

Note : BOL and EOL heating budgets will be provided for cold and hot cases as defined in the next chapters, thiswill avoid to compare erroneously BOL budgets with EOL solar array capacities.

#

Ageing of material properties shall be taken into account in order to provide BOL and EOL budgets.

#


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#

The uncertainty on electronics dissipations shall be taken into account as follows:

Minimum dissipation for the cold cases

Maximum dissipation for the hot cases

#

#

The heating power budgets shall be provided considering a fixed voltage of 50V at the heater inputs.

#

#

The heating power budgets shall be provided for both main and redundant heater circuits (should the redundantheater circuit be different from the main one).

#

#

The heating power budgets shall be provided considering no hardware/software failure.

#

#

The budgets shall be computed by adding arithmetically the contribution of every heating line.

#

#

The budgets shall be provided and updated for each review as follows:

Platform and Payload PDR

Platform and Payload CDR

Platform and Payload QR

FAR.

#

8.2.1 Heating power budgets in cold cases

#

The module contractor shall identify cases potentially worse than the equinox for the calculation of the worstheating power budget.

#

#

The heating power budgets shall be provided at equinox and for the extreme cases identified in the aboverequirement.

#


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#

The module contractor shall provide the average power budgets in stabilised duty cycles conditions in the followingsteady-state modes :

LEOP

On-station

Safe

#

#

The module contractor shall provide the peak (t < 2 s) and the “maximum steady-state” power budgets (t > 2 s) inthe following cases :

In steady state modes:

LEOP

On-station

Safe

In transient modes:

Launch to LEOP

Transitions from normal mode to Decontamination

Return from safe mode

Yaw flip manoeuvres

Eclipse periods

#

Note : the plots showing Power versus Time of the various heating lines will be provided by the contractor in excelfiles.

#

The amplitude and duration of the “max steady-state” power budgets shall be identified (in the plots)

#

#

The frequency of the peaks shall be identified (in the plots)

#

8.2.2 Heating power budgets in hot cases

#

The module contractor shall identify cases potentially worse than the winter solstice for the calculation of the worstheating power budget.

#


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#

The heating power budgets shall be provided at winter solstice and for the extreme cases identified in the aboverequirement.

#

#

The module contractor shall provide the average power budgets in stabilised duty cycles conditions in the followingsteady-state modes :

LEOP

On-station

Safe

#

8.3 Dissipation budgets at module level

#

The budgets shall be provided for Beginning Of Life (BOL) and End Of Life (EOL) conditions.

#

#

Ageing effect on units shall be taken into account in order to provide BOL and EOL dissipation budgets:

#

#

The uncertainty on units dissipations shall be taken into account in order to provide the following dissipationbudgets:

Minimum dissipation

Maximum dissipation

#

#

For each functional mode, the module contractor shall define the following unit attributes:

status (on/off/stand-by/start-up…)

dissipative assumption (bol, eol, min, max…)

dissipation value

#

#

The dissipation budgets shall be provided considering a fixed voltage of 50V at the unit input.

#

#

The dissipation budgets shall be provided for both main and redundant units (should the redundant unit be differentfrom the main one).


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#

#

The dissipation budgets shall be provided considering no hardware/software failure.

#

#

The time-dependent dissipation shall be identified by providing the relevant amplitude, duration, frequency…

#

Note : the plots showing Dissipation versus time of the various units will be provided by the contractor in excel files.

#

The budgets shall be computed by adding arithmetically the contribution of every unit.

#

#

The budgets shall be provided and updated for each review as follows:

Platform and Payload PDR

Platform and Payload CDR

Platform and Payload QR

FAR.

#


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9. SOFTWARE AND MEMORY

Software budgets are addressed in [AD-40C], Software engineering requirements.

10. RFC

The following requirements are applicable to DCS&GEOSAR payload and to the RF S/S within Satellite platform(PDD and TTC):

# Reference

As a general rule for RFC a sufficient margin shall be demonstrated between the total power received by the RFreceivers considered as victims and their specified susceptibility mask (receiver notches):

As minimum, a safety margin of 6 dB shall be verified by test.

12 dB if verified by simulation / analysis shall be implemented into the design if no test are performed.

#

The verification of these margins shall be achieved by the RFC requirement specifications and RFC analysisreports:

Intercompatibility between D&G and Platform (TTC/PDD) performed at System level

Autocompatibility performed at platform level (TTC vs PDD)

Autocompatibility performed at D&G level (DCS vs GEOSAR)


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11. TREND ANALYSIS

For a limited number of items, trend analysis shall be conducted on key characteristics in order to identify andanalyze abnormal change from the nominal tendency even within the specified limits.

Two types of trend analysis will be conducted:

Trend analysis performed over the equipment produced for the 6 satellites of the MTG program,

Trend analysis for a given key characteristic over production from equipment level to spacecraft AIT.

11.1 Trend Over Equipment production

# Reference

The supplier shall submit for approval the list of critical equipment with associated key parameters that will besubmitted to trend analysis at equipment level

#

# Reference

The supplier shall maintain and provide in Excel format the platform equipment trend analysis

#

11.2 Trend from equipment to spacecraft AIT

# Reference

The platform supplier and the payload supplier shall identify key characteristics that shall be monitored for trendanalysis at their level but also afterwards at spacecraft level.Trend analysis of those characteristics shall be maintained and provided in Excel format.

#

# Reference

Based on inputs provided by the platform and payload suppliers, each satellite prime shall maintain the trendanalysis with measurements achieved during spacecraft AIT.

#


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ANNEX 1 TEMPLATE OF POWER BUDGET

Pmax Ppeak Duration Frequency Pmax Ppeak Duration Frequency0 S A-BUD-310 0 0 0 0

FLEXIBLE COMBINED IMAGER 20 ∑FCI

ICU_units electronics 20

ICU_CCE 20

ICU_operational heaters 20

ICU_survival thermal control 15

LIGTHNING IMAGER 20 ∑LI

DCS & GEOSAR 20 ∑D&G

RMU 10 ∑RMU

PDD S/S 20 ∑PDD

TTC S/S 5 ∑TTC

MECHANISMS S/S 5 ∑Mec

DATA HANDLING S/S 15 ∑DH

PROPULSIONS/S 10 ∑Prop

AOCS S/S 14 ∑AOCS

THERMALS/S 20 ∑Therm

HARNESS S/S 0 ∑Harnes

EPS S/S CONSUMPTION 10 ∑EPS

TOTAL PAYLOAD ∑P/L

TOTAL PLATFORM ∑P/F

TOTAL PLATFORM+PAYLOAD P/L+P/F

Battery Resources BOL Battery -Failures -aging *Dod

R equired power for charging

R equired time for charging

Charging Margin S A-P OW-150

BOL Battery available P ower

Failures

Aging degradations

Battery requested energy (Wh)

BATTER Y DoD

Solar Array Resources Net S/A Power =BOL S/A -degradation-failure*Sunaspect-Margin

S olar Array available power - degradations

2string fails

S un aspect angle

S olar Array Margin 10.0

S YS TE M MAR GIN S A-BUD-320 (% of Total P ower Needs) 10 10% of P/L+P/F

TOTAL POWER NEEDS P/L+P/F+System Margin +Charging Margin

ELECTRICAL POWER SYSTEM MARGIN (Capability -

Loads )Net S/A Power or Battery Resources - Total Power Needs

MTG-I POWER BUDGETUnit

margin (% )

LAUNCH

SUN ECLIPSE

Battery Budget shall detail failure modes,degradation, margins and Dod after maximumeclipse duration. Peak recharge / dischargepower and duration shall be shown

Each power figure shall includethe maturity margin shown

Solar Array shall detail failure modes,degradation, and margins

System margin (10%) of total ofPlatform + Payload

Total Power = all margins + allconsumptions

Comparison of Total Power withresources, value shall be positive

Each defined phase/mode shallprovide Pmax_steady_stateand Ppeak values showingduration & frequency of peaks

Total Platform & Payload consumption Pmaxsteady state & steady state + worst case peak foreach phase/mode


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ANNEX 2 TEMPLATE OF ENERGY BUDGET

0 S A-BUD-310 0 0 0 0 0 0 0

FLEXIBLE COMBINED IMAGER 20 ∑FCI

ICU_units electronics 20

ICU_CCE 20

ICU_operational heaters 20

ICU_survival thermal control 15

LIGTHNING IMAGER 20 ∑LI

DCS & GEOSAR 20 ∑D&G

RMU 10 ∑RMU

PDD S/S 20 ∑PDD

TTC S/S 5 ∑TTC

TTC Rx 5

TTC Tx 5

MECHANISMS S/S 5 ∑Mec

DATA HANDLING S/S 15 ∑DH

PROPULSIONS/S 10 ∑Prop

AOCS S/S 14 ∑AOCS

THERMALS/S 20 ∑Therm

HARNESS S/S 0 ∑Harnes

EPS S/S CONSUMPTION 10 ∑EPS

TOTAL PAYLOAD ∑P/L

TOTAL PLATFORM ∑P/F

TOTAL PLATFORM+PAYLOAD P/L+P/F

Battery Resources BOL Battery - Failures -aging *Dod

R equired power for charging

R equired time for charging

Charging Margin S A-P OW-150

BOL Battery available P ower

Failures

Aging degradations

Battery requested energy (Wh)

BATTER Y DoD

Solar Array Resources Net S/A Power =BOL S/A -degradation-failure*Sunaspect-Margin

Solar Array available power - degradations

2string fails

Sun aspect angle

Solar Array Margin 10.0

SYSTEM MAR GIN S A-BUD-320 (% of Total P ower Needs) 10 10% of P/L+P/F

TOTAL POWER NEEDS P/L+P/F+System Margin +Charging Margin

ELECTRICAL POWER SYSTEM MARGIN (Capability -

Loads )Net S/A Power or Battery Resources -Total Power Needs

Paverage Paverage Paverage Paverage

MTG-I POWER BUDGETUnit

margin (% )

LEOPLAUNCH

SUN ECLIPSE SUN ECLIPSE

Each ∑ line to be the sum of individual power lines related to that subsystem orpayload

Each power figure shall includethe maturity margin shown

System margin (10%) of total ofPlatform + Payload

Total Power = all margins + allconsumptions

Comparison of Total Power withresources, value shall be positive

Each defined phase/mode shallprovide Paverage values

Solar Array shall detail failure modes,degradation, and margins

Battery Budget shall detail failuremodes, degradation, margins and Dodafter maximum eclipse duration


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END OF DOCUMENT

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INTERNAL THALES ALENIA SPACEemits.sso.esa.int/emits-doc/OHBSYS/MTG/MTG-Generic-ADs/... · 2011-04-12 · The Contingency factors to be applied at all levels (equipment/instrument,