7/30/2019 Siemens - Contactor Utilization Categories

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19/6 Siemens IndustryIndustrial Controls Cat

IEC contactor utilization catagories

AppendixGeneral Information

Kind of UtilizationCurrent Categories Typical Applications

AC AC-2 Slip-ring motors: starting, switching offAC-5a Switching of electric discharge lamp controlsAC-5b Switching of incandescent lampsAC-6a Switching of transformers, weldersAC-6b Switching of capacitor banksAC-7a Slightly inductive loads in household appliances and s imilar applicationsAC-7b Motor-loads for household applicationsAC-8a Hermetic refrigerant compressor motor1) control with manual resetting of overload releasesAC-8b Hermetic refrigerant compressor motor1) control with automatic resetting of overload releases

DC DC-6 Switching of incandescent lamps

Special Contactor Utilization Categories

Some contactors also have ratings for thefollowing specialty utilization categories.

For specific applications, please contactyour local Siemens sales office.

Electrical Quantities Symbols According to DIN,VDE and IEC

Contactors designed for interna-tional applications are tested andrated per IEC 947-4. The IEC rat-ing system is broken down intodifferent utilization categories thatdefine the value of the currentthat the contactor must make,maintain, and break. The follow-ing category definitions are themost commonly used for IECContactors.

Ratings for Siemens contactorsper these categories can befound in Section 3.

AC Categories

AC-1

This applies to all AC loadswhere the power factor is at least0.95. These are primarily non-inductive or slightly inductiveloads. Breaking remains easy.

AC-3

This category applies to squirrelcage motors where the breakingof the power contacts wouldoccur while the motor is running.On closing, the contactor experi-

ences an inrush which is 5 to 8times the nominal motor current,and at this instant, the voltage atthe terminals is approximately20% of the line voltage. Breakingremains easy.

AC-4

This applies to the starting andbreaking of a squirrel cage motorduring an inch or plug reverse.On energization, the contactorcloses on an inrush currentapproximately 5 to 8 times the

nominal current. On de-energiza-tion, the contactor breaks thesame magnitude of nominal cur-

rent at a voltage that can beequal to the supply voltage.Breaking is severe.

DC Categories

DC-1

This applies to all DC loadswhere the time constant (L/R) isless than or equal to one msec.These are primarily noninductive

or slightly inductive loads.DC-2

This applies to the breaking ofshunt motors while they are run-ning. On closing, the contactormakes the inrush current around

2.5 times the nominal rated cur-rent. Breaking is easy.

DC-3

This applies to the starting andbreaking of a shunt motor duringinching or plugging. The timeconstant shall be less than orequal to 2 msec. On energiza-tion, the contactor sees current

similar to that in Category DC-2.On de-energization, the contactorwill break around 2.5 times the

starting current at a voltage thmay be higher than the line voage. This would occur when tspeed of the motor is lowbecause the back e.m.f. is lowBreaking is severe.

DC-5

This applies to the starting anbreaking of a series motor duinching or plugging. The timeconstant being less than or eqto 7.5 msec. On energization, contactor sees about 2.5 timethe nominal full load current. O

de-energization, the contactorbreaks the same amount of curent at a voltage which can beequal to the line voltage.Breaking is severe.

1)Hermetic refrigerant compressor motor is a combina-tion consisting of a compressor and a motor, both ofwhich are enclosed in the same housing, with noexternal shaft or shaft seals, the motor operating inthe refrigerant.

Symbol Characteristic Electrical Quantity Symbol Characteristic Electrical Quantity

Ui

Rated insulation voltage to DIN VDE 0110/DIN VDE 0660 Icw

Rated short-time current withstand capacity to IEC 947-1

Ue

Rated operational voltage Ip

Test current (general) to DIN VDE 0660, prospective current to DIN VDE 063U

cRated control voltage (IEC 947-1) at which an operating mechanism I

nBreaking current (r.m.s. value) to DIN VDE 0102

or release is rated, e.g. coil voltage to DIN VDE 0660 Part 102 ip

Peak short-circuit current (maximum instantaneous value) to DIN VDE 0102U

sRated control supply voltage (Control voltage) to DIN VDE 0660 Part 102, IEC 947-1I

kSustained (symmetrical) short-circuit current (r.m.s. value), DIN VDE 0102.

U No-load voltage to IEC 947-2, -3, -5 Rated short-time withstand current to DIN VDE 0660U

rPower-frequency recovery voltage (IEC 947-.) i

pLet-through current of fuses and rapidly operating switching device

Uo

Transformer no-load voltage to DIN VDE 0532 (maximum instantaneous value during the break time) to DIN VDE 010U

kShort-circuit impedance voltage to DIN VDE 0532 I

oNo-load current at the input side of a transformer (unloaded output

Ukr

Rated value of the impedance voltage in % to DIN VDE 0102, 01.90 side) to DIN VDE 0532

In

Rated current to IEC 947-. Ix

Current carrying capacity (ampacity)

Ith Eight-hour-current to DIN VDE 0660, conventional free-air thermal Isr Rated rotor operational current (DIN VDE 0660, IEC 947-1)current to IEC 947- (defined as eight-hour-current) thermally equivalent I

rSetting current (current setting) to DIN VDE 0660

short-time current (r.m.s. value) to DIN VDE 0103 IB

Take-over current

Ithe

Conventional enclosed thermal current R Ohmic resistanceIu

Rated uninterrupted current to IEC 947-1 Sk

Initial symmetrical AC short-circuit power (simplified: apparent short-circuit poIe

Rated operational current X Reactance, reactive impedanceIs

Selectivity (discrimination) limit current (DIN VDE 0660, IEC 947-1) Z Impedance (apparent resistance)Icm

Rated short-circuit making capacity to IEC 947-1 x Factor to determine the peak short-circuit current ipIcn

Rated short-circuit breaking capacity to IEC 947-1Icm

Rated ultimate short-circuit breaking capacity to IEC 947-1