14/1/98 Page 23 Issue H
7.6. Test Trip
The whole tripping circuit of the protection system may be tested by simulating a fault with the
<TRIP> push button. This button is also used to interrogate the relay for its software version
number. In order to enter the test trip mode the user must be in display mode 2 (6.2.2). Upon
pressing the <TRIP> button the display responds with <PSW?>. The password must then be
entered, upon entering the correct password the display indicates the software version number, and
the output relays are operated in a cyclic manner illuminating the S/R, A, & KA LEDS in sympathy.
In order to reset the relay, a single press of the <SELECT/RESET> push button will return to
mode 2, alternatively after approximately 2 minutes the relay will automatically return to the normal
mode ( blank display ) if no activity is noted on the front push buttons.
7.7. Reset
There are two ways in which to reset the MPR 3E5 relay:
7.7.1 Hand reset
By pressing the <SELECT/RESET> for approximately 3 seconds the relay is reset.
7.7.2 Auto-reset at Power Up
After loss of supply voltage and upon its reconnection the unit resets itself and displays P&B.
This resetting of the unit does not effect the set parameters which are stored in an EEPROM.
7.8. Phase Rotation
This feature detects incorrect phase sequence and is only active during a start. This can be used to
detect incorrect phase connections to the motor during commissioning. Ten sequence errors in a row
must be detected in order to trip the relay. The DIP Switch No 2 on the internal 10 way switch-group
must be set to "ON" to enable this feature.
7.9. Setting value calculation
In order to ensure that protection relays form an integral part of any system, a full protection co-
ordination study should normally be undertaken which considers both upstream and downstream
equipment. Further details may be obtained by contacting P&B Engineering.
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General