MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0
MPA3 V6.2 Motor Protection Relay Manual
Page 8
3
Overview of MPA3 V6 Relay
3.1
General Description
The Ampcontrol MPA Motor Protection Relay has been designed to provide optimum overload protection of small to
medium sized 415 V motors used on conveyors, pumps, fans and compressors. It can also be used with higher
voltage motors. In addition to motor protection the relay has features to monitor temperature, provide alarms before
a trip condition and through a 50 record event log allows diagnosis of a problem after a fault has occurred. The
standard current transformers supplied with the MPA Protection Relay enable protection of motors with full load
currents ranging from 5.125 A to 640 A. The selected full load current can be set to one of 224 values across the
range.
The MPA Motor Protection Relay has 5 digital inputs, which feed into a microprocessor unit. The microprocessor has
been programmed to control three output relays: MTR (Main Trip Relay), ALM (Alarm Relay) and AUX (Auxiliary
Relay).
Inputs are also provided for PTC Thermistors and current transformers.
A two-line backlit LCD display used in conjunction with a keypad provides an easy to use interface. The display
provides easy access to all available information. A simple procedure allows adjustment of the relay’s settings.
The Energy Storage Module allows the MPA Relay to function normally for a period of two (2) seconds during an
extreme power dip or power loss.
The MPA’s event log and adjustable settings are battery backed with an approved IS Battery - AUS Ex 01.2533X Ex
ia I (when mains power is de-energised). The battery is not user replaceable (return the MPA Relay to Ampcontrol
for replacement of the approved battery).
The MPA is housed in an enclosure suitable for flush mounting in a 135 mm square cut out and has robust plug in
connectors on the rear.
3.2
Protection Functions
The Ampcontrol MPA motor Protection Relay provides protection functions for:
Overload
Short Circuit
Earth Leakage (Designed and Tested to AS2081.3-1988)
Motor Contactor Fail
Phase Current Unbalance
Undercurrent/Over-current Alarms
Over Temperature - PTC Thermistor
Optional Under-voltage
Optional Insulation Test
Optional PT-100 RTD Temperature Protection
