Setting Example - Thermal Protection - Siemens 7SR17 Rho Manual

2.2 S E
ETTING XAMPLE
The motor full load current (FLC) and start current can be calculated:-
Input power
P.F.
Full load current
CT secondary FLC is:
MotorFLC 86
CT Ratio
Motor starting current can be taken to be the same as the locked rotor current, the motor start CT secondary
current is:
5 x 0.86 = 4.3A (= 4.3 x In)
©2014 Siemens Protection Devices Limited
- T P
HERMAL ROTECTION
Figure 2.2-1 Setting Example – Motor Circuit Data
Output 400
efficiency 0.85 0.955
KVA 493
86.3 Amps
3 kV 3 3 3 .
3 . 1
. 0 86 A ( . 0 86
100
Chapter 7) 7SR17 Rho Applications Guide
493 KVA
In )
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