Power Supply Module; Irig-B Board - GE P741 Technical Manual

P74x/EN FD/Na7
(FD) 9-4
1.1.6

Power supply module

The power supply module provides a power supply to all of the other modules in the relay, at
three different voltage levels. The power supply board also provides the EIA(RS)485
electrical connection for the rear communication port.
On a second board the power supply module contains:
•
relays which provide the output contacts (P742 and P743),
•
an auxiliary power supply (P741).
The power supply module also provides a 48V external field supply output to drive the opto
isolated digital inputs (or the substation battery may be used to drive the optos).
1.1.7

IRIG-B board

This board, which is optional, can be used where an IRIG-B signal is available to provide an
accurate time reference for the relays (P741, P742 and P743). The IRIG-B board can only
be used in P741 relay and is controlled by the main board.
All modules are connected by a parallel data and address bus which allows the processor
board to send and receive information to and from the other modules, as required. There is
also a separate serial data bus for conveying sample data from the input module to the
coprocessor. Following figures show the modules of the relay and the flow of information
between them. There are two independent buses. Through the first bus, the main board
controls the coprocessor board and the IRIG-B board (optional, in P741). Through the
second bus, the coprocessor board controls the input/output boards and input module in
P742 and P743 relays, it controls the communication boards in P741 relay. So the
coprocessor board is controlled by the first bus and controls the second bus. Functionally,
electrically, mechanically both interconnection buses are very similar.
FD
Firmware Design
MiCOM P741, P742, P743