Siemens 3RB12 Instructions Manual page 18

Technical data
Short-circuit
protection
Thermistor
protection
Earth fault
protection
20
Main circuit
Short-circuit protection with fuses for motor feeders with
short-circuit currents up to 50 kA at 690 V, 50/60 Hz (see
data given in catalog)
Control circuit
Fuse links, duty class
Protective circuit-breaker
Thermistor sensor in the motor is connected to terminals
T1/T2
Total cold resistance R
Measuring circuit loading
Voltage at sensor circuit
Response value
Return value
The following information based on sinusoidal fault
currents of 50/60 Hz:
external
Summation current transformers 3UL220.-.A are con-
nected to terminal C1/C2. The pick-up delay is 200 ms ≤
t ≤ 500 ms.
internal
With a motor current between 0.3 and 2 times the set
current, the device trips in the event of an earth-fault cur-
rent of 30% of the set current.
With a motor current between 2 and 8 times the set cur-
rent, the device trips in the event of an earth-fault current
of 15% of the set current.
The pick-up delay is 0.5 to 1 seconds.
gL/gG 6 A
quick-acting 10 A
1.6 A
C characteristic
1.5 kΩ
cold
≤ 5 mW
(at R
cold
≤ 2 V (at R
2.7 to 3.1 kΩ
1.5 to 1.65 kΩ
3ZX1012-0RB12-1AA1
= 1.5 kΩ)
= 1.5 kΩ)
cold