Multifunction Protection and Switchgear Control unit REF542plus
Manual: Motor Protection with ATEX-Certification
5 Setting example
The following paragraph presents an example for setting the motor protection func-
tions which are used for thermal supervision. Special consideration is given to the set-
ting of the following functions:
Rotor block protection
Motor start protection
Thermal overload protection
Number of starts protection
The setting of the unbalanced load protection function, which is needed for the super-
vision of the asymmetrical operating conditions, has been described in the previous
paragraph.
In the following figure an example of the FUPLA – configuration of the function blocks
for motor protection - Block Rotor, Motor Start, Number of Start Supervision and
Thermal overload - are shown.
Figure 11: Example of a FUPLA – configuration for the motor protection
For the setting example, a medium voltage motor is assumed to have the following
relevant data:
Rated motor current I
Mn
91A
Wärmeklasse B
Temperaturklasse T3
Blocking current I
E
7.9
Blocking time t
E
(warm) 8sec
Current transformer rated current 100A/1A
1VTA100114-Rev. 04 en PTMV, 19.01.05 Motorprotection 32 / 66
Valid from Version V4D02
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