Firmware Design P54x/EN FD/La4
MiCOM P543, P544, P545 & P546
(FD) 9-9
FD
2.5.1 Power supply board (including EIA(RS)485 communication interface)
One of three different configurations of the power supply board can be fitted to the relay.
This will be specified at the time of order and depends on the nature of the supply voltage
that will be connected to the relay. The three options are shown in the table below:
Nominal dc range Nominal ac range
24/48 V DC only
48/110 V 40/100 Vrms
110/250 V 100/240 Vrms
The output from all versions of the power supply module are used to provide isolated power
supply rails to all of the other modules within the relay. Three voltage levels are used within
the relay, 5.1 V for all of the digital circuits, 16 V for the analogue electronics, e.g. on the
input board, and 22 V for driving the output relay coils. All power supply voltages including
the 0 V earth line are distributed around the relay via the 64-way ribbon cable. One further
voltage level is provided by the power supply board which is the field voltage of 48 V. This is
brought out to terminals on the back of the relay so that it can be used to drive the optically
isolated digital inputs.
The two other functions provided by the power supply board are the EIA(RS)485
communications interface and the watchdog contacts for the relay. The EIA(RS)485
interface is used with the relay’s rear communication port to provide communication using
one of either Courier, IEC 60870-5-103 or DNP3.0 protocols. The EIA(RS)485 hardware
supports half-duplex communication and provides optical isolation of the serial data being
transmitted and received. All internal communication of data from the power supply board is
conducted via the output relay board which is connected to the parallel bus.
The watchdog facility provides two output relay contacts, one normally open and one
normally closed which are driven by the processor board. These are provided to give an
indication that the relay is in a healthy state.
The power supply board incorporates inrush current limiting. This limits the peak inrush
current, during energization, to approximately 10 A.
2.5.2 Output relay board
The
standard output relay boards of the MICOM P543 and P544 hold seven relays, three
with normally open contacts and four with changeover contacts. The output relay boards of
the P545 and P546 hold eight relays, six with normally open contacts and two with
changeover contacts. The relays are driven from the 22 V power supply line. The relays’
state is written to or read from using the parallel data bus. In a standard configuration, the
P543 and P544 have two output relay boards fitted, and the P445 and P446 have four.
2.5.3 High break relay board
A ‘high
break’ output relay board consisting of four normally open output contacts is available
as an option. These contacts are suitable for breaking loads higher than can be broken with
the standard contacts and are available as follows:
If the high break option is selected in the P543 or P544, these relays will contain one
‘high break’ output relay board to replace one standard board, giving a total of 7 standard
relay outputs and 4 ‘high break’ relay outputs
If the high break option is selected in the P545, these relays will contain two ‘high break’
output relay boards to replace two standard boards, giving a total of 16 standard relay
outputs and 8 ‘high break’ relay outputs
In the P546, two high break options are available. Either two or three ‘high break’ output
relay boards replace the standard boards, giving totals of either 16 standard relay
outputs and 8 ‘high break’ relay outputs, or 8 standard relay outputs and 12 ‘high break’
relay outputs
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