Ampcontrol MPA3 V6.3 User manual

MPA3 V6.3 MOTOR PROTECTION RELAY
(Suitable for Mining Applications)
USER MANUAL
Issue: R0 Nov 2010
CRN: 8168
Ampcontrol User Manual Part No: 143401
Designed and Manufactured in Australia by Ampcontrol CSM Pty Limited.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 1
Safety and other Warnings
WARNING!
This safety alert symbol identifies important safety messages in this manual and
indicates a potential risk of injury or even death to the personnel. When you see
this symbol, be alert, your safety is involved, carefully read the message that
follows, and inform other operators.
CAUTION!
This safety alert symbol identifies important information to be read in order to ensure
the correct sequence of work and to avoid damage or even destruction of the
equipment, and reduce any potential risk of injury or death to the personnel.
Supplementary information not directly affecting safety or damage to equipment. Carefully
read the message that follows, and inform other relevant personnel.
Information concerning possible impact on the environment and actions required for
prevention and proper response.
If this document is being read via a computer the hyper links may be used (Press control and click on the blue
highlighted text to go to that topic).

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 2
Copyright Notice
No part of this publication may be reproduced, transmitted or transcribed into any language by any means without
the express written permission of Ampcontrol CSM Pty Ltd, 7 Billbrooke Close, Cameron Park. NSW 2285,
Australia.
Disclaimer
Ampcontrol CSM Pty Ltd will make no warranties as to the contents of this documentation and specifically disclaims
any implied warranties or fitness for any particular purpose.
Ampcontrol further reserves the right to alter the specification of the system and/or manual without obligation to notify
any person or organisation of these changes.
Before You Begin
We would like to take a moment to thank you for purchasing the MPA3 V6 Motor Protection Relay.
Ampcontrol Electronics Contact details:
Ampcontrol CSM Pty Ltd
7 Billbrooke Close, Cameron Park, NSW, 2285
P [phone] | F [phone]
EMAIL: [e-mail]
WEB: www.ampcontrolgroup.com
WARNING!
To ensure the correct and safe operation of this equipment the user is to
become completely familiar with the safety requirements and correct
operating procedures detailed in this user manual.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 3
Table of Contents:
Safety and other Warnings............................................................................................................................................ 1
Copyright Notice............................................................................................................................................................ 2
Disclaimer...................................................................................................................................................................... 2
Before You Begin .......................................................................................................................................................... 2
Ampcontrol Electronics Contact details: ........................................................................................................................ 2
1Receiving and Storage......................................................................................................................................... 5
1.1 Receiving ........................................................................................................................................................ 5
1.2 Storage after Delivery ..................................................................................................................................... 5
1.3 Unpacking of Equipment ................................................................................................................................. 5
2General safety...................................................................................................................................................... 6
2.1 Personnel Safety Warnings............................................................................................................................. 6
2.1.1 Relevant Personnel............................................................................................................................. 6
2.1.2 Safety Communication ........................................................................................................................ 6
2.2Safe Use of Equipment ................................................................................................................................... 6
2.2.1 Changes to Equipment........................................................................................................................ 6
2.2.2 Equipment Knowledge ........................................................................................................................ 6
2.3 Conditions to Maintain Intrinsically Safe Rating .............................................................................................. 7
3Overview of MPA3 V6 Relay................................................................................................................................ 8
3.1 General Description ........................................................................................................................................ 8
3.2 Protection Functions ....................................................................................................................................... 8
3.3 Optional Monitoring Modules........................................................................................................................... 9
3.3.1 MPA-M ................................................................................................................................................ 9
3.3.2 MPA-I .................................................................................................................................................. 9
3.3.3 MPA-M (e)........................................................................................................................................... 9
4Basic Display Operation....................................................................................................................................... 9
4.1 Status Messages........................................................................................................................................... 10
5Current Related Functions ................................................................................................................................. 11
5.1 Overload Protection ...................................................................................................................................... 11
5.2 Short Circuit Protection ................................................................................................................................. 13
5.3 Phase Current Balance ................................................................................................................................. 13
5.4 Residual Current Signal ................................................................................................................................ 14
6Earth Leakage Protection .................................................................................................................................. 14
7Motor Contactor Fail Protection ......................................................................................................................... 14
8Metering............................................................................................................................................................. 15
9Insulation Test.................................................................................................................................................... 15
10 Under-voltage Trip ............................................................................................................................................. 16
11 PT-100 RTD Temperature Protection ................................................................................................................ 16
12 Analogue Output................................................................................................................................................ 17
13 Communications ................................................................................................................................................ 17
13.1 Modbus Communications........................................................................................................................... 18
13.1.1 Modbus Configuration ....................................................................................................................... 18
13.1.2 Modbus Commands .......................................................................................................................... 18
13.1.3 Modbus Status .................................................................................................................................. 18
13.2 EtherNet/IP Communications..................................................................................................................... 19
14 Energy Storage Module ..................................................................................................................................... 20

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 4
15 MPA Alarm Functions ........................................................................................................................................ 20
15.1 High Current Alarm: ................................................................................................................................... 20
15.2 Overload Alarm:......................................................................................................................................... 20
15.3 Under Current Alarm:................................................................................................................................. 20
15.4 Earth Leakage Alarm: ................................................................................................................................ 20
16 Adjustable Settings ............................................................................................................................................ 21
16.1 Common Settings ...................................................................................................................................... 21
16.2 Modbus Settings ........................................................................................................................................ 21
16.3 Ethernet Settings ....................................................................................................................................... 22
16.4 Changing Settings...................................................................................................................................... 22
17 Digital Inputs ...................................................................................................................................................... 23
18 Output Relays .................................................................................................................................................... 23
19 Event Log........................................................................................................................................................... 23
20 Advanced Display Operation ............................................................................................................................. 25
21 Time & Date....................................................................................................................................................... 25
22 MPA Specifications............................................................................................................................................ 26
23 MPA Comms. Address Table............................................................................................................................. 28
24 Maintenance & Disposal .................................................................................................................................... 33
24.1 Equipment Maintenance ............................................................................................................................ 33
24.2 Disposal of System Parts........................................................................................................................... 33
25 Equipment List ................................................................................................................................................... 34
25.1 Base Models and Options Part Nos........................................................................................................... 34
25.2 Miscellaneous Extras ................................................................................................................................. 34
Appendix A –Drawings ............................................................................................................................................... 35
Appendix B –Approvals .............................................................................................................................................. 42

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 5
1 Receiving and Storage
1.1 Receiving
All possible precautions are taken to protect the equipment against damage or losses during shipment, however
before accepting delivery, check all items against the packing list or Bill of Lading. If there are shortages or evidence
of physical damage, notify Ampcontrol immediately.
Notify Ampcontrol within 7 days (maximum) in case of shortages or discrepancies, according to the packing list. This
action will help ensure a speedy resolution to any perceived problems. Keep a record of all claims and
correspondence. Photographs are recommended.
Where practicable do not remove protective covers prior to installation unless there are indications of damage.
Boxes opened for inspection and inventory should be carefully repacked to ensure protection of the contents or else
the parts should be packaged and stored in a safe place. Examine all packing boxes, wrappings and covers for
items attached to them, especially if the wrappings are to be discarded.
1.2 Storage after Delivery
When the equipment is not to be installed immediately, proper storage is important to ensure protection of equipment
and validity of warranty.
All equipment should be stored indoors protected from the elements in a cool dry area. If storing on the ground,
ensure that the storage area is not an area where water will collect.
1.3 Unpacking of Equipment
The method of packing used will depend on the size and quantity of the equipment. The following cautions should be
interpreted as appropriate.
CAUTION!
Take care when unpacking crates as the contents may have shifted during transport.
Make sure that cable drums are securely attached to their shipping pallets before
attempting to move them (if applicable).
The disposal of packaging materials, replaced parts, or components must comply with
environmental restrictions without polluting the soil, air or water.
Ensure that any timber and cardboard used as packaging is disposed of in a safe and
environmentally responsible manner.
Where possible, dispose of all waste products i.e. oils, metals, plastic and rubber products
by using an approved recycling service centre.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 6
2 General safety
2.1 Personnel Safety Warnings
2.1.1 Relevant Personnel
Ensure all personnel directly responsible or involved with the installation, operation and maintenance of the
equipment reference this manual in conjunction with any relevant risk assessments to identify all foreseeable
hazards.
2.1.2 Safety Communication
All safety instructions and design requirements within this manual must be communicated to all users. These
requirements are necessary to identify and control any foreseeable risk associated with this piece of equipment. In
the event of any damage or malfunction that results in the potential to harm the health or safety of any person; the
owner/operator should notify the manufacturer immediately.
2.2 Safe Use of Equipment
Equipment supplied has been manufactured within the guide lines of the relevant Australian Standards and state
legislative requirements. Equipment identified within this manual has been designed for a specific intended purpose;
therefore any modification or damage must be reported to the manufacturer for repair.
The instructions within this manual must be observed as an aid towards achieving maximum safety during operation.
2.2.1 Changes to Equipment
Changes in the design and modifications to the equipment are not permitted
2.2.2 Equipment Knowledge
Experience with, or understanding of, this equipment is essential for the safe installation and removal of the
equipment. If in doubt, contact Ampcontrol immediately.
Mechanical and or Electrical installation, and maintenance of plant and equipment, must only be carried out by
appropriately trained, qualified and competent personnel.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 7
2.3 Conditions to Maintain Intrinsically Safe Rating
Refer also to Certificate of Conformity in Appendix B –Approvals at the back of this manual of this manual
The ISB/1 Battery Assembly Module is certified as complying with the relevant standards for intrinsically safe
electrical equipment with the following grouping and classification:
Ex ia I 150°C (-20°C to +40°C ambient temperature range) Underground Coal Mines
WARNING!
To ensure that this equipment does not contravene the Certificate of
Conformity certain conditions must be met; they are as follows:
a) The following entity parameters must be observed:
Um = 132V
Entity Parameters
Apparatus
Uo
(V)
Io
(mA)
Group I
Co
(µF)
Lo
(mH)
ISB/1
3.7
0.5
10000
1000
b) The ISB/1 Battery Assembly Module shall be installed in an appropriately certified enclosure
providing a Degree of Protection of at least IP20.
c) The ISB/1 Battery Assembly Module shall only be removed or replaced in a nonhazardous area.
d) The ISB/1 Battery Assembly Module is considered intrinsically safe only when the mains power and
any other power sources are de-energised.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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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

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 9
3.3 Optional Monitoring Modules
3.3.1 MPA-M
This optional monitoring module (MPA-M) can be utilised to provide the following features:
Five PT-100 RTD inputs, which are arranged in two groups; three for the stator and two for the bearings.
RS485 Modbus RTU communication port that can be connected to Motor Starter PLC's, or a central
monitoring system, for continuous monitoring and fault-finding.
A 0-20 mA/4-20 mA Analogue Output.
3.3.2 MPA-I
This is an optional insulation test module which allows frequent testing of motor insulation.
3.3.3 MPA-M (e)
This optional monitoring module has the same features as the MPA-M module except the RS485 Modbus
communication port is replaced by an EtherNet/IP communications port.
4 Basic Display Operation
The facia of the MPA Motor Protection Relay has a two line 16-character backlit LCD display, Status LED and a
tactile keypad.
The layout of the display structure is shown on the ‘MPA Display Map’. The display level is changed with the
Up/Down arrow keys and the Left/Right arrow keys control the display Position. See drawing ‘MPA Display Map’
MPAB003,Appendix A –Drawings.
The ENT and ESC keys are used to modify settings and provide hyper jump access to the display structure.
The Reset key allows reset following a trip condition.
The Status LED is a single bi-coloured LED that can be viewed some distance from the relay. Status indication is as
follows:
MPA Status
LED Colour
LED Flash
OK
Green
4 Hz
Alarm
Red
4 Hz
Trip
Red
1 Hz
The ‘Motor Status Page’ is the default screen on power up and shows the current status of the MPA Protection
Relay. A one-line status message is displayed and if more than one message is active the display cycles through all
active messages at 1 second intervals.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 10
4.1 Status Messages
The following table (Table 4.1) shows a list of the twenty-three status messages and the category (type) of the
messages. Messages are cleared according to their message category.
Type 1: Messages are triggered by their respective functions and cleared by operating the <RESET> key/digital
input.
Type 2: Messages are triggered and cleared automatically.
Type 3: Messages are triggered by their respective trip functions. Messages are cleared by closing the lock input,
and then operating the <RESET> key/digital input, and then releasing the lock input.
Message and Type
Comment
Motor O/L Trip
1/2
Over Current Function Tripped
Short Cct Trip
3
Short Circuit Function Tripped
Cur. bal. Trip
1
Phase Current Balance Function Tripped
Earth Leak Trip
1
Earth Leakage Function Tripped
Residual I Trip
1
Residual Current Function Tripped
Thermistor Trip
1
Thermistor PTC Function Tripped
Under Volts Trip
1
Under Volts Function Tripped
MPA Memory Error
1
Corrupted memory in relay’s stored settings
RTD Group1 Trip
1
RTD Group 1 Function Tripped
RTD Group2 Trip
1
RTD Group 2 Function Tripped
Motor Cont. Fail
1
Main Contactor Fail Function Tripped
Insulat.Test Trip
1
Insulation Test Function Tripped
High Cur. Alarm
2
Phase current above set threshold level
Over Load Alarm
2
Thermal Accumulator above set threshold level
Under Cur. Alarm
2
Phase current below set threshold level
Earth Leak Alarm
2
Earth leakage Current is above the set threshold level
RTD Group1 Alarm
2
Group 1Temperature above set threshold level
RTD Group2 Alarm
2
Group 2 Temperature above set threshold level
Insulat. Test Alarm
1/2
Test result at alarm level
Testing Insulat.
2
In process of Insulation Test
IT Enable Open
2
Insulation test disabled.
Insulat. Test OK
2
Insulation Test above the set threshold
Motor Stopped
2
MCI Open
Motor Amps:
2
MCI Closed
Table 4.1

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 11
5 Current Related Functions
5.1 Overload Protection
The motor overload function is based on a thermal model of the motor. The three phase currents are squared to
provide the I2Rheating input to the motor model. The selected ‘Stopped Cooling Ratio’ determines the cooling
output for the model.
The state of the thermal model is shown by the ‘Thermal Accumulator’, which can be viewed on the 'Current/Volts
Information' level on the display. The thermal accumulator represents the motor temperature. When it reaches 100%
a “Motor Overload”trip occurs.
The full load current is selected via the ‘I (100%)’ setting (Level 7, Position 1) and can be set between 5.125 A and
640 A in 224 increments as shown in Table 5.1, ‘Current Settings’.
MPA Full Load Current Selection Table - Amps
5.125
7.000
10.000
14.00
20.00
28.0
40.0
56
80
110
160
220
320
440
5.250
7.125
10.25
14.25
20.5
28.5
41
57
82
112
164
224
328
448
5.375
7.250
10.50
14.50
21.0
29.0
42
58
84
114
168
228
336
456
5.500
7.375
10.75
14.75
21.5
29.5
43
59
86
116
172
232
344
464
5.625
7.500
11.00
15.00
22.0
30.0
44
60
88
118
176
236
352
472
5.750
7.625
11.25
15.25
22.5
30.5
45
61
90
120
180
240
360
480
5.875
7.750
11.50
15.50
23.0
31.0
46
62
92
122
184
244
368
488
6.000
7.875
11.75
15.75
23.5
31.5
47
63
94
124
188
248
376
496
6.125
8.000
12.00
16.00
24.0
32.0
48
64
96
126
192
252
384
504
6.250
8.500
12.25
17.00
24.5
34.0
49
68
98
128
196
256
392
512
6.375
8.750
12.50
17.50
25.0
35.0
50
70
100
136
200
272
400
544
6.500
9.000
12.75
18.00
25.5
36.0
51
72
102
140
204
280
408
560
6.625
9.250
13.00
18.50
26.0
37.0
52
74
104
144
208
288
416
576
6.750
9.500
13.25
19.00
26.5
38.0
53
76
106
148
212
296
424
592
6.875
9.750
13.50
19.50
27.0
39.0
54
78
108
152
216
304
432
608
13.75
27.5
55
156
312
624
640
Table 5.1 Current Settings

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 12
The trip time is selected via the ‘6xI Trip t’ setting (Level 7, Position 2). It is a function of the current and the selected
trip time curve. The drawing ‘MPA Motor Overload and Short Circuit Trip Times’, MPAB007, in Appendix A –
Drawings shows the trip time curves.
The fifteen motor overload curves allow trip settings from 3 to 40 seconds at six times FLC and are shown for both
cold and hot conditions. The hot curve corresponds to the trip time after the motor has been running at the selected
full load current indefinitely.
The trip time can be calculated as follows:













1238.1
100 %1238.1
ln53.31
2
2
I
A
I
CTimeTrip
Where:
C = Curve Selected
I= Current (FLC = 1)
A% = Initial Thermal Accumulator Value
The motor manufacturer's data should always be consulted to select the appropriate settings for the motor being
protected. Typically, the capacity of a cold motor is given at six times its rated current.
The MPA Relay's trip curves can then be used to select the trip time curve, which best suits the motors overload
capacity.
The motor overload trip latches once the thermal accumulator reaches 100% and can only be reset once the thermal
accumulator falls below a preset value. The pre-set value is selected via the ‘O/L Reset’ setting (Level 7, Position 3)
and can be set to 30%, 40%, 50%, 60%, 70%, 80%, 90%, A-30%, A-40%, A-50%, A-60%, A-70%, A-80%, A-90%.
The A- settings automatically reset a motor overload trip once the thermal accumulator falls below the set value.
Otherwise the trip has to be reset manually by pressing the keypad ‘RESET’ button or activating the ‘RESET’ digital
input once the thermal accumulator has fallen below the set value.
An emergency restart on a hot motor can be achieved by zeroing the thermal accumulator memory. This is done by
closing the E/start input and reset key/digital input simultaneously for 1.5 seconds.
CAUTION!
Repeated attempts to restart the motor in this condition may damage
the motor.
The ‘Stopped Cooling Ratio’ modifies the cooling output of the thermal model when the motor is stopped. This can be
used to account for reduced cooling capacity of the motor when it is not running (motor run status monitored via MCI
digital input).
The ratio is selected via the ‘S-Cool Ratio’ setting (Level 7, Position 4) and is adjustable from 1.0 to 5.0. A cooling
multiplier of 1 means the cooling is independent of whether the motor is running or not - e.g. a water-cooled motor.
Protection for a fan-cooled motor is based on a setting of 2.5, however, for the best protection consult the motor
manufacturer.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 13
Ibal =
5.2 Short Circuit Protection
The short circuit function has a definite time characteristic. If the current exceeds the selected level for the pre-set
time then a trip occurs. The short circuit function trips the auxiliary relay. (The AUX relay is normally energised, and
drops out when tripped).
The short circuit trip level is selected via the ‘SC I Trip’ setting (Level 7, Position 6) and is a multiple of the selected
full load current, from 3.0 to 10 times FLC, in steps of 0.5. The trip level may be set to ‘off’ to disable the SC
protection.
WARNING!
Setting the trip level to ‘OFF’ disables the SC function and is intended to only ever
be used with coordinated SC tripping circuit breakers or when the SC function is
performed external to the MPA. Use extreme caution when choosing this option.
The trip time is selected via the ‘Sc Trip t’ setting (Level 7, Position 7) and is adjustable from 20 to 160 ms. See
Drawing MPAB007 in Appendix A –Drawings.
To reset the relay following a short circuit trip it is necessary close the lock input, then operate the reset key/digital
input, and then release the lock input.
5.3 Phase Current Balance
The current balance measurement ‘Ib’ is displayed on the ‘Current/Volts Information’ Page, Level 1, Position 1 and is
calculated as:
MAX Ix 100%
Iave
Where:
Iave = Average of the 3 phase currents
MAX I= The maximum deviation of a phase current from the average
Phase current balance protection is selected via the ‘I Bal Trip’ setting (Level 7, Position 5).
The trip level is selectable at 5%, 10%, 20%, 50% and off.
The phase current balance protection is inhibited until the average current exceeds both 20% of the selected full load
current and the selected balance trip level.

MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
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MPAB010 Rev0 MPA3 V6.2 Motor Protection Relay Manual
Page 14
5.4 Residual Current Signal
The three phase current signals are summed electronically in the MPA to produce a residual current signal that can
be used to detect earth fault currents. If the residual current signal exceeds the trip level for the selected trip time, a
trip occurs, tripping the MTR relay. The fault is latched.
To reset the relay following a residual current trip, operate the reset key/digital input.
The % residual current is displayed as ‘Ir’ on the ‘Current/Volts Information’ Page, Level 1, Position 2.
The trip level is selected via the ‘Ires Trp’ setting (Level 7, Position 14) and is adjustable from 10% to 100% FLC.
The trip time is selected via the ‘Ir Time’ setting (Level 7, Position 15) and is adjustable from 100 ms to 5 sec.
Setting the trip level to ‘Off’ disables this function.
The residual current function can be used even if a core balance toroid is used for earth
leakage protection. It can be used to provide some detection of wiring/CT/internal relay
faults.
6 Earth Leakage Protection
The earth leakage protection function is designed and tested to AS2081.3-1988 and uses a 100:1 core balance
toroid to measure the earth fault current. A definite time operating characteristic is provided with adjustable trip
sensitivity and time delay. If the earth leakage signal exceeds the trip level for the selected trip time, a trip occurs,
tripping the MTR relay. The fault is latched.
The % leakage current is displayed on the 'Current/Volts Information' Page as ‘Ie’ shown as a % of the selected trip
level. When the leakage reaches 100% for the selected time delay a trip occurs.
To reset the relay following an earth leakage trip, operate the reset key/digital input.
The trip level is selected via the ‘EL:’ setting (Level 7, Position 11) and is adjustable between 0.001 A to 0.005 A x
CT ratio. Trip settings are 100-500 mA with the approved 100:1 Toroid. Setting the trip level to ‘Off’ will disable this
function.
The time delay is selected via the ‘EL Time’ setting. Settings are Instantaneous and are adjustable between 155 ms
and 475 ms.
For alarm functions see ‘MPA Alarm Functions’, Section 15.
7 Motor Contactor Fail Protection
The status of the motor contactor is monitored via the ‘MCI’ digital input. If the MPA trips its MTR relay then it expects
to see the MCI open. Failure to open within 1 second will cause a ‘Motor Contactor Fail’ trip that operates the AUX
relay. The AUX relay should be arranged to provide backup tripping of the motor, usually through a main circuit
breaker.
To reset the relay following a motor contact failure trip, operate the reset key/digital input.
The status of the MCI input can be viewed on the ‘MPA I/O Status Information’ Page, Level 5, Position 1.

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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

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The ‘testing’ phase takes 3 seconds during which time the IT input must remain active in order to obtain a valid
result. The last IT result is retained in memory and displayed until a subsequent test or power down.
The measurement range is 125 Mdown to 0.8 M, with <0.8 Mdisplayed for values less than 0.8 M.
The trip level is selected via the ‘ITst Trp’ setting (Level 7, Position 17) and is adjustable between 1.0 Mand 100
M.
The alarm level is selected via the ‘ITst Alm’ setting (Level 7, Position 18) and is adjustable between 1.0 Mand
100 M.
A trip takes priority if both trip and alarm conditions occur as a result of an IT.
IT alarms self-clear when a subsequent IT result is greater than the selected alarm value. They can also be reset
manually by operating the reset key/digital input.
IT trips are latched and prevent subsequent IT’s until the trip is manually reset by operating the reset key/digital input.
Setting either the ‘ITst Trp’ or ‘ITst Alm’ setting to ‘OFF’ disables that function.
10 Under-voltage Trip
The optional Insulation Test Module (MPA-I) allows Under-voltage protection that is enabled as soon as the main
contactor is closed (indicated by closing the MCI input). If any of the phase voltages drop below the selected trip
setting of the nominal line voltage for 1.5 Seconds then the MTR relay is de-energised.
To reset the relay following an under-voltage trip, operate the reset key/digital input.
The trip level is selected via the ‘UV Level’ setting (Level 7, Position 19) and is adjustable from 40% to 95%. Setting
the trip level to ‘Off’ disables this function.
11 PT-100 RTD Temperature Protection
The optional Monitoring Module (MPA-M) allows temperature monitoring of 5 PT-100 RTDs, connected in 3-wire
mode. The three-wire connection allows compensation of installation lead resistance. The RTD inputs are configured
as ‘Group1’ RTD’s (1, 2 and 3) and ‘Group 2' RTD’s (4 and 5). Each Group has a separate alarm and trip level.
Group 1 (G1) is intended for monitoring stator temperature while group 2 (G2) is intended for bearing temperature.
The Trip levels are selected via the ‘RTD G1 T:’ and/or ‘RTD G2 T:’ settings (Level 7, Position 20 and 22) and are
adjustable from 60°C to 200°C. If the measured value exceeds the trip level for 2 seconds, a trip occurs. Trip’s are
latched, and cannot be reset by the reset/digital input until the temperature falls back below the trip threshold.
Setting the trip level to ‘Off’ disables this function.
The Alarm levels are selected via the ‘RTD G1 A:’ and/or ‘RTD G2 A:’ settings (Level 7, Position 21 and 23) and are
adjustable from 50°C to 200°C. If the measured value exceeds the alarm level for 2 seconds, an alarm occurs.
Alarm’s self clear once the measured value falls below selected value for 2 seconds. Setting the alarm level to ‘Off’
disables this function.
A trip takes priority if both trip and alarm conditions occur as a result of a RTD’s temperature.

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The RTD temperatures for group 1 and group 2 can be viewed on the ‘Temperature Information’ Page, Level 2,
Positions 1 and 2 respectively. The measurement range is 0°C to 210°C. Values greater than 210°C represent an
error condition as follows:
Error
Comment
246
Error code 246 results if the RTD terminals are left
open circuit or the RTD resistance rises above 330 .
Unused RTD inputs can be terminated with a 100 
resistor (0C) to avoid the error code.
245
Error code 245 results if the RTD is short-circuited or
its resistance falls below 80 .
The RTD’s will operate correctly if the combined installation cable resistance to the PT-100 RTD is less than 40 .
12 Analogue Output
The optional Monitoring Module (MPA-M) provides an isolated analogue output configurable as 0-20 mA or 4-20 mA.
The output is selected via the ‘An OP:’ setting (Level 7, Position 24) to continuously monitor one of the following
sections:
Trip Accumulator (20 mA = 100%)
Average Current (20 mA = 1000%)
Earth Leakage (20 mA = 100%)
RTD Temp (0-200 °C) (20 mA = 200°C)
Current Balance (20 mA = 100%)
Phase Voltage (A phase) (20 mA = 120%)
The analogue output status is shown on the ‘MPA I/O Status Information’ Page, Level 5, Position 4. The value
shown for ‘Analog Out’ is related to the analogue output current according to:
Iout (mA) = Displayed Value x 8.1458 x 10-05
13 Communications
When the MPA is ordered with an optional monitoring module a communications port is provided. This allows for the
connection of the MPA to PLC or SCADA systems. Two different monitoring modules are available providing a
choice between RS485 Modbus RTU and EtherNet/IP.
With either communications option, the same data is available over the network. See Section 23, ‘MPA
Communications Address Table’ for accessible data.

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13.1 Modbus Communications
13.1.1 Modbus Configuration
The baud rate is selected via the ‘Modbus:’ setting (Level 7, Position 25) and is selectable between 1200 and 9600
Baud, with even, odd, or no parity. One stop bit is used in conjunction with parity, while two stop bits are used with no
parity.
The half-duplex 3-wire RS485 communications interface allows up to 31 devices to be multi-dropped onto a single
master communication line. The MPA’s Modbus Slave address is selected via the ‘Modbus Ad:’ setting (Level 7,
Position 26) and is adjustable between 1 and 31.
13.1.2 Modbus Commands
The following Modbus commands are supported:
Modbus CMD
Comment
03
Read Holding Registers
04
Read Input Registers
06
Store Single Register
16
Store Multiple Registers
Valid read registers are in the range from 1 to 96. An attempt to read a register outside this range will result in an
exception scan. Currently, only the first 64 registers contain valid data. The range from 65 to 96 is for future
expansion The range from 65 to 96 are also write addresses, the only active write address is 65 which is folded back
to the read only address 20.
Supported Modbus exception responses are:
Modbus Exception
Comment
01
Illegal Function
02
Illegal Data Address
03
Illegal Data Value
13.1.3 Modbus Status
The MPA Modbus status is shown on the ‘MPA I/O Status Information’ Page, Level 5, Position 4 and indicates the
following:
Status
Comment
No Opt Card
No monitoring card installed
No Mbus RxD
Monitoring card installed, but there
has not been a valid Modbus
transaction in the last 30 seconds
Online…OK
Monitoring card installed, a valid
Modbus transaction has occurred
in the last 30 seconds

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13.2 EtherNet/IP Communications
13.2.1 Ethernet Network Configuration
The Ethernet connection allows for the setting of the MPA’s IP Address, Default Gateway Address and Subnet Mask.
The IP Address can only be set statically using the MPA configuration menu. Dynamic address configuration
protocols such as DHCP or BOOTP cannot be used.
Both the IP address and the default gateway are set using four individual parameters; one for each byte of the
address. The subnet mask is set as a single number between 0 and 32. This number is the number of bits used in
the subnet mask.
Example configuration:
IP Address: 192.168.10.25
Default Gateway: 192.168.11.254
Subnet Mask: 255.255.0.0
IP Address
IP Addr 3
IP Addr 2
IP Addr 1
IP Addr 0
192
168
10
25
Gateway
Gateway 3
Gateway 2
Gateway 1
Gateway 0
192
168
11
254
SubnetMsk
16
13.2.2 EtherNet/IP Settings
The MPA provides process data to the originator of an EtherNet/IP connection using I/O messaging. The connection
can be established by creating a generic Ethernet Module and setting the following parameters:
Assembly Instance
Size
Input
101
65
Output
102
1
Configuration
128
0
Comms Format:
Data - INT
Requested Packet Interval:
> 150 ms
The MPA data should be available as Input data once an EtherNet/IP Connection has been established.