IMM 8001/8002 – Digital Motor Protection Relay
ICE / CEE
____________________________________________________________________________________________
IMU307-1 GB Ind. B
41
TESTS : verification of THERMAL IMAGE protection [49]
CONNECTION, COEFFICIENT OF CORRECTION
See previous page
Sequence of operations to be performed
Results to be obtained
Thermal unit check with operating level correction by stator RTDs (IMM
8002)
Put into service protection 49-Ith>
Put into service temperature correction (in function [26]).
Connect at least a RDT or a RTDs simulator,
and put this RTD into service :
the average temperature measured
Tsm
is the temperature of the RTD or
RTDs in service.
Set insulator maximum temperature
Tmax.
The thermal state evaluated by the temperature RTDs is equal to :
The operating level of the thermal unit is compensated in the following way :
Apply current so as to cause changes in the thermal state up to 100 %, then
stabilise the thermal state at this value. Therefore, we must have
θ
=
1.00
Cause variations in the temperature measured by the RTD :
The thermal unit operating level depends on the measured temperature when
θ
s
is greater than
θ
The operating level
Ith²>
decreases and becomes equal to 100 % when the
measured temperature increases. If
θ
and
Ith²
= 1, then we have :
For
θ
s
=
1.14
, the thermal unit operating level changes to 100%, which
corresponds to a RTD temperature equal to or greater than :
Example : Tmax = 140°C
The thermal unit operating level is reached for
154°C
Note : the compensation does not relate to the thermal alarm Ith>AI
θ
s =
C
40
Tmas
C
40
Tsm
°
−
°
−
Ith²> = 1.14
θ
/
θ
s
1 = 1.14 x 1 /
θ
s and
θ
s = 1.14
1.14
=
C
40
Tmas
C
40
Tsm
°
−
°
−
1.14
=
C
100
C
40
Tsm
°
°
−
Tsm = 114 + 40 = 154°C
on reaching the operating level :
the selected relay must be energised,
the fault message must be displayed,
the Start Function and Internal Trip indicator LEDs
illuminate simultaneously.