410009 Rev F Electrical Installation Technical Referencegemenergycapstone.com/.../410009F_TR_ElectricalInstallation.pdf · Technical Reference: Capstone MicroTurbine Electrical Installation

410009 Rev F (October 2013) Page 1 of 31 Capstone reserves the right to change or modify, without notice, the design, specifications, and/or contents of this document

without incurring any obligation either with respect to equipment previously sold or in the process of construction.

Capstone Turbine Corporation 21211 Nordhoff Street Chatsworth CA 91311 USA Phone: (818) 734-5300 Fax: (818) 734-5320 Web: www.capstoneturbine.com

Technical Reference Capstone MicroTurbine Electrical Installation

Capstone Turbine Corporation 21211 Nordhoff Street Chatsworth CA 91311 USA Technical Reference: Capstone MicroTurbine Electrical Installation



Capstone Turbine Corporation

21211 Nordhoff Street Chatsworth CA 91311 USA

Telephone: (818) 407-3600

Facsimile: (818) 734-5382

Website: www.capstoneturbine.com

Capstone Technical Support

Telephone: (866) 4-CAPSTONE or (866) 422-7786

E-mail: [email protected]




Table of Contents 1. Introduction ............................................................................................................................. 5 2. Reference Documents ............................................................................................................ 6 3. General Requirements ............................................................................................................ 6

3.1. Protective Earth (PE) / Chassis Ground ........................................................................ 6 3.2. Grounding the Microturbine Neutral ............................................................................... 7

3.2.1. Grounding Location .......................................................................................... 7 3.2.2. Grounding Potential .......................................................................................... 7

3.3. Overcurrent Protection & Disconnecting Devices .......................................................... 8 3.4. Power Bay Connections ................................................................................................ 9 3.5. MultiPac Power Connections ....................................................................................... 15

4. Grid Connect ......................................................................................................................... 16 4.1. Phase Sequence ......................................................................................................... 17 4.2. Transformer Applications and Impedance ................................................................... 17 4.3. Allowable Connections ................................................................................................ 17

5. Standalone Mode .................................................................................................................. 20 5.1. Output and Load Specification ..................................................................................... 20 5.2. Phase Sequence ......................................................................................................... 20 5.3. Transformers for Highly Non-Linear Loads .................................................................. 20 5.4. Transformer Sizing Recommendation ......................................................................... 21 5.5. Generic Diagrams of Isolation Transformer Installation ............................................... 21 5.6. Allowable Connections ................................................................................................ 24

6. Dual Mode ............................................................................................................................. 24 6.1. Installations Requiring 4-Pole Motorized Grid Breaker ................................................ 24 6.2. Allowable Connections ................................................................................................ 24

7. C65 Hybrid UPS .................................................................................................................... 25 7.1. Surge Protection Device .............................................................................................. 26 7.2. Allowable Connections ................................................................................................ 26

8. Input Impedance ................................................................................................................... 30 8.1. Example 1: Model C30 - Considering 1 Microturbine .................................................. 30 8.2. Example 2: Model C65 - Considering 1 Microturbine .................................................. 30 8.3. Example 3: Considering 3 Microturbines ..................................................................... 31




List of Figures Figure 1. Recommended Device Layout ...................................................................................... 9 Figure 2. C30 User Connection Bay .......................................................................................... 11 Figure 3. C65 User Connection Bay .......................................................................................... 11 Figure 4. C65 HUPS User Connection Bay ............................................................................... 12 Figure 5. C200 User Connection Bay ........................................................................................ 13 Figure 6. C1000 User Connection Bay ...................................................................................... 14 Figure 7. Power Connections: MultiPac System – Ground Rod At Each Unit ........................... 15 Figure 8. Power Connections: MultiPac System – Common Ground Rod ................................. 16 Figure 9. Connection to 480V Wye Service - Direct Connection ............................................... 18 Figure 10. Connection to Non-480V Wye Service – Autotransformer with Grounded Neutral ... 18 Figure 11. Connection to Wye-Wye Service: Isolation Transformer .......................................... 19 Figure 12. Connection to Wye-Delta Service: Isolation Transformer ......................................... 19 Figure 13. Connection to Non-480V Wye Service – Autotransformer with Floating Neutral ..... 20 Figure 14. Isolation Transformer Installation Example ............................................................... 22 Figure 15. Isolation Transformer Installation Example ............................................................... 22 Figure 16. Isolation Transformer Installation Example ............................................................... 23 Figure 17. Paralleling Transformers Installation ........................................................................ 23 Figure 18. Stand Alone Connections: Three-Phase Loads ........................................................ 24 Figure 19. Dual Mode Connections: Using an Isolation Transformer ........................................ 25

List of Tables Table 1. Referenced Documents ................................................................................................. 6 Table 2. Overcurrent Protection Sizing ........................................................................................ 8 Table 3. N – L1 – L2 – L3 – DC Terminal Block Specifications ................................................. 10 Table 4. Protective Earth (PE) / Chassis Ground Terminal Block Specifications....................... 10 Table 5. Grid Connect Allowable Configurations Matrix ............................................................ 17 Table 6. HUPS Allowable Connections ...................................................................................... 26




1. Introduction This document presents electrical installation information for the Capstone MicroTurbine systems.

Capstone Microturbines (with the exception of the C65 Hybrid UPS) provide two operational modes:

Grid Connect Mode (GC)

Stand Alone Mode (SA)

GC mode provides alternating current (AC) electrical power in parallel with a utility grid or with another generation source. GC mode includes built-in utility-synchronization capability and protective relay functions. In this mode, the microturbine acts as a current source, controlling its current output to meet the commanded power output at the rated voltage.

SA mode provides alternating current (AC) electrical power for standby, backup, or remote off-grid purposes. In this mode, the microturbine acts as a voltage source, regulating its voltage output to the configured voltage and frequency settings.

A Dual Mode (DM) connection option (which requires a Dual Mode System Controller), is available and allows automatic transition between GC and SA modes.

Multiple systems can be combined and controlled as a single larger generating source, commonly known as a MultiPac. Operation as a MultiPac is available for SA, GC, and Dual Mode operation.

The C65 Hybrid UPS product is unique since there are two AC connections, one for grid and one for critical load. The grid connection operates in a mode very similar to GC mode, and the critical load connection operates in a mode very similar to SA mode. This product’s unique electrical configuration is considered separately in Section 7.

This document describes proper electrical interconnection for the Alternating Current (AC) output versions only. Refer to our Hybrid Electric Vehicle documentation for Direct Current (DC) model installation instructions.

CAUTION: All of the allowable utility service connections for the various microturbine operating modes are presented in this document. Consult Capstone if your utility service connections do not agree with those presented in this document.




2. Reference Documents Table 1 provides a list of Capstone documents referenced in this Technical Reference.

Table 1. Referenced Documents

Document Part No Description

400017 C65 Microturbine User’s Manual

400030 C30 Microturbine User’s Manual

410000 C30 Electrical Technical Reference

410001 C60/C65 Electrical Technical Reference

410032 MultiPac Technical Reference

410033 Protective Relay Functions Technical Reference

410066 C200 Technical Reference

410072 C1000 Technical Reference

460062 C200 CARB Product Specification

480009 C30 and C60 HEV Application Guide

523646 C200 with HRM Outline and Installation (O&I) Drawing

3. General Requirements It is the responsibility of the installer to supply all ancillary electrical equipment such as electrical cable, switchgear, transformers, and disconnects through which the microturbine delivers its output power. The equipment must be capable of safely handling the maximum potential loads, and must meet all applicable local and national regulations. This section outlines general requirements for all Capstone products.

WARNING: It is essential that the installer consult all of the applicable codes and industry standards before connecting the interface wiring for the microturbine. Notice that a qualified electrician may be required to perform this work.

3.1. Protective Earth (PE) / Chassis Ground All Capstone Microturbine products must have protective earth (PE) grounding for the chassis. A separate ground lug is included in the user connection bay for this purpose. Commonly this PE is provided by a ground rod installation. Using a single PE connection for multiple microturbine chassis grounds is acceptable. This PE may or may not be the same ground used for the microturbine neutral; if it is not, the PE for the chassis ground and the ground for the neutral should be at equivalent potentials, with respect to earth.

All electrical wiring, including protection and grounding, must conform to all local and national electrical codes and regulations.

All drawings in the document will indicate the protective earth (PE)/ chassis ground by “PE/G”.




3.2. Grounding the Microturbine Neutral All installations, for both GC and SA modes, must have the neutral wire properly grounded. This provides a ground reference for proper operation. Neglecting to properly ground the microturbine system (that is, no neutral-to-ground connection, or more than one neutral-to-ground connection) can cause damage to the microturbine system.

All electrical wiring, including protection and grounding, must conform to all local and national electrical codes and regulations.

3.2.1. Grounding Location

It is recommended to ground the neutral wire(s) in only a single location, unless local code requires more than one connection. For example, it is sometimes required by local code to ground the neutral before the conductor leaves one building and travels into another, in case the neutral is broken during earthmoving activities. In the case of multiple grounding points, these grounding points should be at equivalent earth potentials; otherwise circulating currents can occur and provide a poor reference for operation.

For GC installations, the recommended location of the neutral-to-ground connection is at the utility service panel or the utility service transformer. A neutral-to-ground connection is often already present at the wye utility service transformer.

For SA and DM installations, the recommended location of the neutral-to-ground connection is at the microturbine service panel. Use of four-pole breakers may necessitate multiple neutral-to-ground connections, and more information is provided on this subject in Section 6. If multiple neutral-to-ground connections are required, please contact Capstone Applications Engineering for approval.

3.2.2. Grounding Potential

WARNING: A solid earth ground1 of the microturbine neutral is MANDATORY for successful operation.

A high-resistance ground should not be necessary, due to the very low fault current contribution of the microturbine(s)2. However, a high-resistance ground may be possible, and will require a modification to the microturbine as well as additional external surge protection equipment (to be supplied by the installer). Please contact Capstone Applications Engineering for approval.

WARNING: Any high-resistance grounding scheme MUST BE APPROVED BY CAPSTONE PRIOR TO COMMISSIONING.

1 Measurable at 5 ohms or less ground resistance per NEC, NFPA, and IEEE recommendation 2 Approximately 2X nominal current




3.3. Overcurrent Protection & Disconnecting Devices Overcurrent protection is required for each microturbine, usually by circuit breaker or fused disconnect. This overcurrent protection device must be installed between the microturbine and the electrical service panel. The type and fault-current ratings of the device must meet maximum current and voltage ratings for each microturbine model as well as meet all local codes and specifications. Recommended sizing for overcurrent protection devices is as follows:

Table 2. Overcurrent Protection Sizing

Microturbine Model Recommended Trip Setting3

C30 60 Arms

C65 (UL, HUPS, and all other) 125 Arms

C65 (CE) 150 Arms

C200 400 Arms

C600 1200 Arms

C800 1600 Arms

C1000 2000 Arms

If a fused disconnect switch is used instead of circuit breaker, time delay fuses are not required. Fast acting, current limiting fuses are recommended. It is recommended to install the fuses on the microturbine side of the switch.

CAUTION: A lockable disconnect device should be located within sight of the microturbine.

Any disconnect device should always have lockout provisions to facilitate safe maintenance operations. In the case that the service panel and microturbine are very near, it may be acceptable to use the overcurrent protection device as this lockable disconnect; please note that most circuit breakers will require additional hardware to become “lockable”. In the case of a long distance between the microturbine and the service panel, this should be a separate lockable switch. Figure 1 shows the recommended configuration for a four unit multipack of microturbines.

3 Recommended trip setting based on 125% of maximum microturbine steady state current as listed in the C65 Electrical Technical Reference (410001). For example, the nominal steady state current of a C200 is 310 Arms. 125% x 310 Arms = 387.5 Arms. This is rounded up to 400Arms.




Service Panel

LockableDisconnect

CircuitBreaker

MainCircuit

Breaker

MT

ToMT2

ToMT3

ToMT4

Note: Locate the lockable disconnect within viewing distance of the microturbine

To Primary Service Panel or Utility Service

Transformer

Figure 1. Recommended Device Layout

Always refer to the latest national and local codes relative to your location to determine the proper connection requirements.

3.4. Power Bay Connections The User Connections Bay for each microturbine model is shown below.

NOTE: In accordance with UL 2200, the conductor gauge and torque specifications for both N – L1 – L2 – L3 – DC and grounding terminal blocks are listed in Table 3 and Table 4 respectively. This is applicable for copper and aluminum conductor types.

NOTE: Final selection of conductor sizing must respect all local and national codes. The wire gauge information in Table 3 and Table 4 is only a listing of physical capabilities of the terminal blocks, and should not be substituted for a proper engineering analysis for conductor gauge..




Table 3. N – L1 – L2 – L3 – DC Terminal Block Specifications

Microturbine Connection

Wire Size Torque Spec4 Max # of Conductors per phase

(AWG / MCM) (mm2) (Lb-in) (N-m)

Min Max Min Max

C30/C65/

C65 HUPS AC 6 2/0 13 67 180 20.3 1

C200 /

C65 HUPS DC 4

500 MCM

21 250 375 42.4 1

C600/C800/ C1000

2 600

MCM 34 300 375 42.4 4

Table 4. Protective Earth (PE) / Chassis Ground Terminal Block Specifications

Microturbine Connection

Wire Size Torque Spec4 (AWG) (mm2)

(Lb-in) (N-m) Min Max Min Max

C30 / C65 14 2 3 34 120 16.9

C200 14 2/0 3 67 180 20.3

C600 / C800 / C1000

Installer must land ground wire on ground bus bar using appropriate hardware

4 Torque value listed is based upon maximum wire size using UL486 recommendation. Smaller torque values may be possible for small gauge wire. Refer to UL486 for recommended torques using wire gauges smaller than the maximum torque.




Figure 2. C30 User Connection Bay





Figure 4. C65 HUPS User Connection Bay

DC Battery (+) Terminal

DC Battery (-) Terminal

PE/G

Auxiliary DC Gas Pack Connection with Fusing









Neutral Bus Bar

Phase C Bus Bar

Phase B Bus Bar

Phase A Bus Bar

Ground Bus Bar




3.5. MultiPac Power Connections Refer to the MultiPac Technical Reference (410032) for details on MultiPac operation. Power connections between the MultiPac systems will be necessary, and these connections must consider the proper phase wiring, neutral wiring, and grounding connections between the various systems. Refer to Figure 8 for electrical connection diagram for permitted MultiPac connections.

Protective earth (PE) / chassis grounding can either be a ground rod at each unit (as shown in Figure 7), or can be a single, common ground rod at the service panel (as shown in Figure 8). For simplification of the following connection diagrams in this document, this multipac is represented electrically by a set of terminals L3, L2, L1, and N labeled “Single or Multipac Connections”.

Figure 7. Power Connections: MultiPac System – Ground Rod At Each Unit




L3

L2

L1

G

N

Mic

rotu

rbin

e #

1M

icro

turb

ine

#N L3

L2

L1

G

N

Microturbine or Multipac

Service Panel

MT Circuit Breaker

PE/G

ViewableLockable

Disconnect

L3

L2

L1

N

Main Circuit Breaker

Single Unit or Multipac

Connections

MT Circuit Breaker

NOTE: All wiring shown should be connected regardless of connection type.

Figure 8. Power Connections: MultiPac System – Common Ground Rod

4. Grid Connect Table 5 presents the various allowable connections for the Grid Connect operating mode. The table will show important attributes for comparison including standards compliance, wiring, etc. No 3-wire delta utility service connections are allowed5. For details on each configuration, refer to the figure number shown for that configuration.

5 No three-wire delta utility service connections are allowed because the phase-to-ground voltages float, and over time, these voltages (with respect to ground) become unbalanced and cause microturbine nuisance trips. In addition, the phase-to-ground voltages can reach levels that can break the insulation in the IGBTs-to-ground and cause equipment failure.




Table 5. Grid Connect Allowable Configurations Matrix

Figure No. Standards Compliance Utility Service

Transformer Type UL1741 CE/Other Wye Delta

9 X X X None

10 X X X Autotransformer with Grounded Neutral

11 X X X Wye/Wye Isolation

12 X X X Wye/Delta Isolation

13 X X Autotransformer with Floating Neutral

4.1. Phase Sequence The output phase sequence is L1 to L2 to L3. Notice that improper phase sequence connections may cause the microturbine to trip. It is the installer’s responsibility to verify the proper phase connections between the microturbine and the grid.

4.2. Transformer Applications and Impedance A voltage transformer for the microturbine will be required if the circuit voltage is outside the 400 to 480 Volts AC range.

All GC mode installations with transformers between the microturbine and the grid6 must consider maximum grid impedance. Proper sizing of transformers in the installation is required to limit the impedance seen by the microturbine. For impedance limits required for installation of each microturbine model, refer to the Electrical Specification documents referenced in Table 1. Refer to Input Impedance on page 30 for example calculation of the impedance of the line run and transformers to the utility source.

4.3. Allowable Connections

Figure 9 through Figure 13 present the permitted utility (or transformer) connections for Capstone products.

6 To a point in the distribution grid where the voltage is 6 kV or higher




Single Unit or Multipac

ConnectionsUtility

ServiceL3

L2

L1

N

PE/G

Figure 9. Connection to 480V Wye Service - Direct Connection

Figure 10. Connection to Non-480V Wye Service – Autotransformer with Grounded Neutral




Figure 11. Connection to Wye-Wye Service: Isolation Transformer

Figure 12. Connection to Wye-Delta Service: Isolation Transformer




Figure 13. Connection to Non-480V Wye Service – Autotransformer with Floating Neutral

5. Standalone Mode

5.1. Output and Load Specification The microturbine output consists of three phases and a neutral. The current in each phase need not be balanced, as long as the electrical current limits per phase are respected. Loads may be connected phase-phase or phase-neutral. The nominal Stand Alone voltage setting is available between any two phases.. For current and voltage specifications of each microturbine model, refer to the Electrical Specification documents referenced in Table 1.

5.2. Phase Sequence For SA installations, the output phase rotation sequence is L1 to L2 to L3. Notice that improper phase connections can damage the connected loads or cause microturbine trips. Capstone cannot be held responsible for equipment damage caused by improper connections. It is the installer’s responsibility to verify the proper phase connections between the microturbine and the load(s).

5.3. Transformers for Highly Non-Linear Loads For any SA installation with highly non-linear loads, an isolation transformer is required. This transformer functions as a harmonic filter and provides additional benefits for motor starting and kVA margin.

Highly non-linear loads are defined as:

Any loads causing the site current THD to be greater than 8%




Non-linear lighting loads: Fluorescent ballasts and sodium lamps

There are two major benefits that are worth consideration. First, the energy storage in the transformer windings will reduce voltage drop during DOL (across-the-line) motor starts. Second, for 400V applications, using an operating voltage of 480V on the microturbine side of the transformer will provide up to 20% higher kVA margin available for starting large electric loads.

For sites requiring an isolation transformer, the recommended configuration is as follows:

- Delta connection on microturbine side.

- Wye connection is recommended on load side. However, delta connection on load side is also acceptable if required by installation.

- 480 volts output setting on microturbine side (may not be commercially available in your country, so 400V is acceptable, but this limits any motor starting benefits).

- Impedance between 4-8%. Lower impedance will provide overall better voltage regulation, but may require a soft start ramp to be configured on the microturbines for installations with 3 or more microturbines.

Autotransformers are not allowed as an alternative to the required isolation transformer, since they do not provide the galvanic isolation and delta winding which minimize the transmission of harmonics.

5.4. Transformer Sizing Recommendation For any SA installation requiring a transformer, the following sizing recommendations are provided. Per the discussion in Section 5.3, the recommended configuration is one or two large transformers after the paralleling of the microturbines, so these recommended sizes can be summed based on the total number of units connected to the same paralleling bus.

o 45 kVA per C30 system

o 112.5 kVA per C65 system





5.5. Generic Diagrams of Isolation Transformer Installation Figure 14 through Figure 16 represent examples of allowed configurations for SA and DM installations. Capstone recommends any transformers should be placed after the paralleling of the Multipac.

Figure 17 represents a connection that is not recommended, but may be possible. If individual transformers are used before the paralleling of the microturbines, these transformers must be matched with identical impedance, kVA rating, wiring sequence, and phase difference (primary to secondary).




Figure 14. Isolation Transformer Installation Example






Figure 17. Paralleling Transformers Installation




5.6. Allowable Connections

Figure 18. Stand Alone Connections: Three-Phase Loads

6. Dual Mode An installation designed to switch between GC and SA operation is identified as a Dual Mode installation, and must meet the installation requirements for both GC and SA operation, including the required isolation transformer for SA operation. Automatic transfer between modes may be accomplished with the optional Capstone Dual Mode System Controller. Refer to the Dual Mode System Controller Technical Reference (410071) for details.

Whether manual or automatic, the electrical conversion from one mode to the other must be planned with care, particularly the neutral and ground connections. Safety requirements, code requirements, and functional requirements must all be met.

6.1. Installations Requiring 4-Pole Motorized Grid Breaker In some parts of the world, 4-pole circuit breakers are required, which will break the neutral wire as well as the three phases. Given the requirement of grounding the neutral wire in both SA mode and GC mode (discussed in Section 3.2), there may need to be a neutral-grounding relay capable of keeping the neutral grounded when the DMSC switches the motorized breaker open. This construction and theory of operation is discussed in the Dual Mode System Controller Technical Reference (410071). The below allowable connections assume 3-pole breakers, but are otherwise valid for 4-pole breaker installations, assuming the proper neutral-grounding considerations.

6.2. Allowable Connections Figure 19 presents indirect connection using the Dual Mode System Controller. The DMSC is installed between the isolation transformer and the protected loads, and the utility or local transformer.




L3L2L1

GN

Single Unit or MultiPac

ConnectionsIsolation

Transformer

Must be continuous

with the utility ground

Protected Loads

Refer to Figures 10 & 11

for isolation transformer connection

details

Dual Mode System

ControllerWye Utility Service or

Local Transformer

PE/G

Figure 19. Dual Mode Connections: Using an Isolation Transformer

7. C65 Hybrid UPS The C65 Hybrid UPS microturbine comes with two AC power connections, the GLCM and LLCM. The GLCM connection should connect to the utility grid source, and the LLCM output should connect to the critical load bus. Due to the unique design of the C65 Hybrid UPS microturbine compared to other Capstone products, external isolation transformers are required on both connections to avoid momentary short circuit through the internal power electronics.

The required LLCM and GLCM AC power connections must be three-phase, four wire un-grounded wye.

WARNING: The neutral wire should NOT be grounded at the microturbine connection bay or at either isolation transformer. The only ground connection should be the chassis ground connection at each C65 Hybrid UPS microturbine. This is due to the fact that the positive DC bus is grounded internally. The chassis grounding is required per normal installation guidelines listed in Section 3.2.

.

CAUTION: The maximum length for the conductor between each microturbine AC connection and the isolation transformer is 10 meters.

All conductor should be run using grounded conduit. Exceeding this length could result in excessive EMF generation, which could interfere with operation of sensitive electrical equipment. Contact Capstone Applications Engineering with any questions.

The DC external battery should be connected with proper polarity of positive and negative verified. There should be no power grounding on the external battery string, since this is provided internally to the Hybrid UPS Microturbine. For the DC battery connection, a DC circuit




breaker disconnect must be included between the batteries and the unit. See the C65 Hybrid UPS Application Guide (Refer to Table 1) for more details on battery system specification.

Three- or four-wire connections are allowable, as shown in Figure 20 and Figure 21. For four-wire connections, the critical loads need not be balanced as long as the current limits per phase are not exceeded.

WARNING: Three-wire critical load connections are allowable as long as the neutral on the critical load side of the isolation transformer is grounded AND the critical loads are BALANCED. No unbalanced critical loads are allowed for 3-wire critical load connections.

7.1. Surge Protection Device Due to the unique internal architecture of the C65 Hybrid UPS system, a surge protection device must be installed on the grid-side connection of the isolation transformer for each unit. Capstone will provide the device required for UL installations as well as any other 4-wire 480Y/277V installations. All other wiring configurations will require an alternative surge protection device, which must be specified with the assistance of Capstone Applications Engineering. The spec sheet and installation documents from the manufacturer are listed in Appendix of the C65 Hybrid UPS Application Guide (480049).

The required connections for the surge protection device are described in detail in Figure 20 through Figure 22 below. The device should be mounted with leads as short as possible, recommended not to exceed 1m in length.

7.2. Allowable Connections Table 6. HUPS Allowable Connections

Figure No.

Grid Connection

Wiring

Critical Load Connection

UL2200/1741 Compliance

Isolation Transformer

Windings

Surge Protection Device

4-wire 3-wire

4-wire 3-wire

16 X X Yes

Wye/Wye Supplied by Capstone

17 X X Yes

Wye/Wye Contact

Applications Engineering

18 X X No

Wye/Delta Contact

Applications Engineering




Figure 20. 4-Wire HUPS Installation




Figure 21. 3-Wire HUPS Installation with Wye/Wye Transformers




Isolation Transformer Utility Service

L3

L2

L1

N

Cri

tica

l Lo

ad L3

L2

L1

N

PE/G

Isolation Transfer (Wye-Wye)

Cri

tica

l Lo

ad

Ser

vice

Pan

el

Elec

tric

al C

onne

ctio

n Ba

y

Gri

dD

C B

atte

ry

+-

to External Battery System

Optional Lockable Disconnect

CircuitBreaker

Optional Lockable Disconnect

CircuitBreaker

SurgeProtection

Device

Figure 22. 3-Wire HUPS Installation with Wye/Delta Transformers




8. Input Impedance Refer to Table 1 for the Electrical Specification documents listing input impedance requirements of each microturbine model

Examples of the total electrical input impedance calculations which detail the values considering the microturbine output looking towards the utility are provided in the following paragraphs.

NOTE: Input impedance calculations are for Grid Connect operation only.

8.1. Example 1: Model C30 - Considering 1 Microturbine

Total Impedance for all conductors: ZL = 0.5%, ZR = 1.0%

Inductive: ZL (Total) = 5.6% (30/45) + 6.4% (30/45) + 5% (30/60) + 0.5% = 11% (Value exceeds acceptable limit of 10%)

Resistive: ZR (Total) = 1.7% (30/45) + 1.9% (30/45) + 1.6% (30/60) + 1% = 4.22% (Value is within acceptable limit of 5%)

8.2. Example 2: Model C65 - Considering 1 Microturbine Total Impedance for all conductors: ZL = 0.5%, ZR = 1.0%

ZL (Total) = 5.6% (65/75) + 6.4% (65/75) + 5% (65/100) + 0.5% = 14.2% (Value exceeds acceptable limit of 10%)

ZR (Total) = 1.7% (65/75) + 1.9% (65/75) + 1.6% (65/100) + 1% = 5.16% (Value exceeds acceptable limits of 5%)

30 KVAMicroTurbine

240 V208 V480 V

45 kVA 45 kVA 60 kVA

Utility 5 kV

65 KVAMicroTurbine

240 V208 V 480 V

75 kVA 75 kVA 100 kVA

Utility 5 kV

ZL1 = 5.6% ZL2 = 6.4% ZL3 = 5% ZR1 = 1.7% ZR2 = 1.9% ZR3 = 1.6%

ZL1 = 5.6% ZL2 = 6.4% ZL3 = 5% ZR1 = 1.7% ZR2 = 1.9% ZR3 = 1.6%




8.3. Example 3: Considering 3 Microturbines Total Impedance for all conductors: ZL = 0.5%, ZR = 1.0%

Note: In these calculations, the number 120 represents the sum of the Microturbine outputs (30+30+65)

Microturbine #1 (30 kVA):

ZL (MT1) = 5.6% (30/45) + 7.2% (125/500) + 5% (125/2000) + 0.5% = 6.3% (Value is within acceptable limits)

ZR (MT1) = 1.7% (30/45) + 1.8% (125/500) + 1.3% (125/2000) + 1% = 2.7% (Value is within acceptable limits)


ZL (MT2) = 5.6% (30/45) + 7.2% (125/500) + 5% (125/2000) + 0.5% = 6.3% (Value is within acceptable limits)

ZR (MT2) = 1.7% (30/45) + 1.8% (125/500) + 1.3% (125/2000) + 1% = 2.7% (Value is within acceptable limits)


ZL (MT3) = 4.3% (65/112.5) + 7.2% (125/500) + 5% (125/2000) + 0.5% = 5.1% (Value is within acceptable limits)

ZR (MT3) = 1.4% (65/112.5) + 1.8% (125/500) + 1.3% (125/2000) + 1% = 2.3% (Value is within acceptable limits)

MicroTurbine #1 30 kVA



480 V

480 V

480 V

480 V

480 V 4160 V

500 kVA 2000 kVA

112.5 kVA

45 kVA

45 kVA

Utility34.5 kV

ZL1=5.6%, ZR1=1.7%

ZL2=5.6%, ZR2=1.7%

ZL3=4.3%, ZR3=1.4%

ZL4 = 7.2% ZL5 = 5% ZR4 = 1.8% ZR5 = 1.3%

65 kVA