IMM 8001/8002 – Digital Motor Protection Relay
ICE / CEE
____________________________________________________________________________________________
IMU307-1 GB Ind. B
93
Diagnostic aid in the event of malfunction
Verification of current circuit connections
The I1 and I3 currents can be read in A and In machine. Compare their amplitude with the currents which
actually flow.
The positive phase sequence and negative phase sequence components can be displayed. Their value gives
information on the good connection of the current transformers :
good connection :
Ipos = I
Ineg = 0
direction of rotation reversal : Ipos = 0
Ineg = I
open phase :
Ipos = 0.577 I
Ineg = 0.577 I
direction reversal for a phase
Ipos = 0.577 I
Ineg = 1.15 I
direction reversal for phase +
direction of rotation reversal
Ipos = 1.15 I
Ineg = 0.577 I
If the present value seems incorrect, it is required to check the connection direction of the current
transformers.
Verification of voltage circuit connection
The connection of the voltage circuit which corresponds to the 2 currents is possible by consulting the
measured active power P and the measured reactive power Q.
With the motor operating, the
active power P
it consumes must be
positive (no),
and the
reactive
power Q
must be
inductive (no)
(current behind voltage).
If the power value or the sign seem incorrect, check the connection of the voltage transformer.
Other abnormal cases
No display illumination : check relay consumption, knowing P = about 10 W.
Relay operation but no circuit breaker operation : check trip loop continuity.
