IMM 8001/8002 – Digital Motor Protection Relay
ICE / CEE
___________________________________________________________________________________________
_
IMU307-1 GB Ind. B
32
IMPORTANT NOTE :
All the current-related values (Operating levels and displays) are expressed in
In machine,
except for the earth fault which is expressed in
IN CTs
(residual connection) or
IN0
ring CT.
Coefficient
K
(
RATED VALUES
chapter) adjusts the machine nominal value to the CT
nominal value with :
K = In machine / IN CT
Example : In machine = 250A, IN CT's = 300A: K = 250/300 = 0.83
In addition, the following must be implemented :
matrix to route the various protections to relay T, alarms to relays A and B, and start
authorisation functions to relay P.
possible enabling of the digital inputs.
disabling of RTDs inputs which are not used (IMM 8002).
Before performing the tests, it is preferable to inhibit all the functions, and to perform the tests
function by function. All the protections used will be put into service at the end of the tests.
Note
: the parameters set for the nominal current and voltage must be such that the power does not
exceed 100 MW.
5.2. TEST EQUIPMENT
The relay tests can be performed with single-phase or three-phase current as chosen. Therefore, it
will be possible to use a single-phase or three-phase voltage/current injection set with a timer and an
automatic injection cut-off system.
Good measurement accuracy can only be obtained with injection power supplies delivering as stable
as possible currents and voltages.
Measurement accuracy
During tests on site, it is normal that operating level-related and response time-related inaccuracies
are greater than those recorded in the laboratory.
Operating level-related inaccuracies come from :
the stability of the injected currents,
the shape of the currents and voltage,
the accuracy of the relay and devices used.
