MPA3 V5.4 MOTOR PROTECTION RELAY MANUAL
Issue: R0, CRN: 8168, Date: 11/2010
MPAB009 Rev0
MPA3 V5.4 Motor Protection Relay Manual
Page 14
8
Metering
The MPA Motor Protection relay provides the following information:
Phase Currents
Current Balance
% Residual Current
% Leakage Current
Trip Accumulator (thermal capacity indicating how close to a trip condition)
Result of Insulation Test (MPA-I option)
% Phase voltage (MPA-I option)
Stator Temperature (MPA-M option)
Bearing Temperature (MPA-M option)
9
Insulation Test
The optional Insulation Test Module (MPA-I) allows the insulation resistance of 415 V motors and/or installations to
be tested with 500 VDC to earth. Selectable trip and alarm thresholds can be triggered if the resistance to earth is
too low. This test can only be performed when the motor is stopped (MCI open). The external ‘Insulation Test
Enable’ (ITE) terminals must also be bridged to allow a test to be performed.
An insulation test (IT) is activated by the option selected by the ‘
ITst Mode
’ setting (Level 7, Position 16). The
options are:
Setting
Comment
Di1
Di1 digital input activates IT
Key
Keyboard Test Key activates IT
Di1/Key
Either one of the above activate IT
Off
IT disabled
The ‘
ITstatus
’ is shown on the ‘Insulation Test Information’ Page, Level 4, Position 1 and indicates the following:
Status
Comment
No ITM
IT Module not installed
Mtr Run
Motor Running (IT Disabled)
Enable?
IT Module installed but Enable Input (ITE) not bridged
Test?
Ready to test, waiting IT input according to ‘IT Mode’ setting
Testing
Test in progress. IT input must remain for three (3) seconds
Test OK
IT result was OK, message remains until loss of IT input
Alarmed
IT result triggered an alarm, message remains until loss of IT
input
Tripped
IT result triggered a trip, message remains until trip is reset
