MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0
MPA3 V6.2 Motor Protection Relay Manual
Page 20
14
Energy Storage Module
The Energy Storage Module (MPA-E) allows the MPA Relay to function normally for a period of two (2) seconds
during an extreme power dip or power loss.
15
MPA Alarm Functions
The MPA has several standard alarm functions. If any are triggered, the Alarm Relay (ALM) picks up. Each has a
selectable alarm level, and can be disabled. Generally the alarms are self-resetting once the alarm condition is
removed. Optional modules MPA-I and M contain alarm settings for Insulation Test and Temperature Monitoring.
15.1
High Current Alarm:
This is triggered by the phase currents exceeding the selected threshold. It is selected via the ‘
HI I Alarm:
’
setting (Level 7, Position 8) and is adjustable from 100% to 600% FLC. The highest of the three phase
currents is used. Time delay = 1 sec. Setting the alarm level to ‘Off’ disables this function.
15.2
Overload Alarm:
This is triggered by the thermal accumulator exceeding the selected threshold. It is selected via the ‘
O/Load
Alm:
’ setting (Level 7, Position 9) and is adjustable from 50% to 95%. Time delay = 2 Sec. A motor overload
trip overrides this alarm. Setting the alarm level to ‘Off’ disables this function.
15.3
Under Current Alarm:
This is triggered by the phase current falling below the selected threshold. It is selected via the ‘
LO I Alm:
’
setting (Level 7, Position 10) and is adjustable from 32% to 96%. This alarm is only activated when the motor
is running (MCI input closed). Time delay = 2 sec. Setting the alarm level to ‘Off’ disables this function.
15.4
Earth Leakage Alarm:
This is triggered when the earth leakage current exceeds a set level. The alarm level is selected via the ‘
E/L
Alarm:
’ setting (Level 7, Position 13) and can be set to 20%, 50%, and 80%. The earth leakage alarm has a
time delay of 1 second and auto resets when the earth leakage current falls below the selected level. There is
also a special setting called EL-T which causes the alarm relay to activate whenever the earth leakage trip
activates i.e. the earth leakage alarm bit follows the earth leakage trip bit. Setting the alarm level to ‘Off’
disables this function.
