0611CT1603

400 Hz Applications

Impact on Protective Devices

The current in 400 Hz systems have higher losses caused by eddy currents and an increase in the skin effect (reduction in the useful cross-sectional area of conductors). The higher losses cause additional temperature rise in circuit breakers subjected to the higher frequency current. To remain within the rated temperature-rise limits of devices, current derating is required. On circuit breakers equipped with thermal-magnetic trip units, the current rating (In) must be derated and the magnetic trip setting Im must be increased.

NOTE: The following derating information pertains to 3Ø applications. For 1Ø applications, please contact Schneider Electric for additional information.

Breaking Capacity in 400 Hz, 480 V Systems

Power levels of 400 Hz applications rarely exceed a few hundred kW with relatively low short circuit currents, generally not exceeding four times the rated current.

Circuit Breaker

Max. Breaking Capacity AIR at 400 Hz

B-frame

10 kA

Thermal-Magnetic Trip Units

Thermal-magnetic trip units require the current rating (In) to be derated and the magnetic trip setting (Im) to be increased.

Current Rating (In) and Magnetic Trip Setting (Im) Rerating

Circuit Breaker

Maximum Setting Coefficient

Max Ir Setting at
400 Hz

Magnetic Im Coefficient at 400 Hz

B-Frame, 125 A

0.9

112

1.6

Shunt Trip (MX) or Undervoltage Trip (MN) Voltage Release at 400 Hz and 440 V

Undervoltage releases (MN) rated 24 Vac/dc, 48 Vac/dc, or 110/130 Vac/dc are 400 Hz compliant with their nominal voltages. For voltages greater than 110/130 Vac/dc, please contact Schneider Electric for additional information.

For all voltages of shunt trips (MX), please contact Schneider Electric for additional information.

Power Loss and Resistance Per Pole

Thermal power loss values are used to calculate total temperature rise in the equipment in which the circuit breakers are installed. The values indicated in the tables below are typical values for a device at full rated load and 50/60 Hz.

  • Power Loss per Pole (P/pole) in Watts (W)

    • The value indicated is the power loss at In, 50/60 Hz, for a three-pole or four-pole circuit breaker. Measurement and calculation of power loss are carried out in compliance with Annex G of standard IEC 60947–2.

  • Resistance per pole (R/pole) in milliohms (mΩ)

    • The value of the resistance per pole is provided as a general indication for a new device.

    • The value of the contact resistance is determined on the basis of the measured voltage drop, in accordance with the manufacturer’s test procedure.
      NOTE: This measurement is not sufficient to determine the quality of the contacts, i.e. the capacity of the circuit breaker to carry its rated curent.

  • Calculation of the total power loss

    • Total power loss at full rated load and 50/60 Hz is equal to power losses per pole multiplied by the number of poles.

Power Loss and Resistance Per Pole

Rating

Power Loss
P / Pole (W)

Resistance per Pole
R Total / Pole (mΩ)

15

10.7

2.4

20

5.7

2.3

25

4.6

2.9

30

2.9

2.6

35

2.7

3.3

40

2.3

3.6

45

2.0

4.0

50

1.8

4.6

60

1.5

5.3

70

1.1

5.5

80

1.0

6.5

90

0.9

7.6

100

0.8

7.6

110

0.6

7.8

125

0.6

9.4

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