Ampcontrol HPB - Short Circuit; Phase Current Balance

Ampcontrol Pty Ltd – ABN 28 000 915 542
HPB USER MANUAL
HPBB012 Version 9 – March/2020
Uncontrolled Copy - Refer to Ampcontrol Website for Latest Version
Page 24 of 61
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HPBB003, in APPENDIX A: DRAWINGS and Extremely Inverse Over-current Curves, HPBB001, in
APPENDIX A: DRAWINGS, show the trip characteristics.
7.3 Short Circuit
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.
When a trip occurs, the “SC” LED on the display module flashes and the open collector output on the
HPB Relay is switched on to provide monitoring if required.
To reset the relay following a short circuit trip it is necessary to hold the lock input closed and then close
the reset button.
The HPB Relay can be programmed so that a short circuit trip will operate either the “CBR” relay or the
“MCR” Relay. This can be achieved by selecting the required relay at the “SC Relay” selection in the
non-volatile memory (See Section 9, User Adjustable Settings). Normally the “CBR” selection would be
used.
If “MCR” is selected then the user must ensure that the interrupting device that is operated by the MCR
Relay has sufficient current interrupting capacity at the system voltage for the situation in which it is
installed.
The short circuit trip level is adjustable from 3 to 10 times (full load current in 0.5 increments. The trip
time is selectable from 40 to 160ms.
7.4 Phase Current Balance
Phase current balance protection is selected via the “Cur Bal trip” selection (See Section 9, User
Adjustable Settings). The current balance measurement is displayed on the Remote Display Module and
is calculated as:






Where:


 
  
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.
If the trip level is exceeded, a time is trigger. If the imbalance remains above the set level for more than
two seconds the relay trips. The event logs records “Ibal” to differentiate it from a true over-current trip.
The status of the time is displayed adjacent to the “Ibal” value (level 5, position 2) on the HDM Remote
Display Module. A trip condition occurs when the timer reaches 100%.