Auxiliary Power Supply; Irig-B Board (In P741); Second Rear Communications & Intermicom Teleprotection Board - GE P741 Technical Manual

P74x/EN FD/Na7
(FD) 9-16
2.10

Auxiliary power supply

In P741 the power supply module contains main power supply and an auxiliary power
supply. The auxiliary power supply adds power on 22 V rail for the up to 7 communication
boards within the relay.
The three input voltage options are the same as for main supply. The relay board is provided
as an alone board.
2.11

IRIG-B board (in P741)

The IRIG-B board is an order option that can be fitted in the P741 to provide an accurate
timing reference for the relays (P741, P742 and P743 (via the P741)). This is available as a
modulated or de-modulated option depending on the requirements. The IRIG-B signal is
connected to the board via a BNC connector on the back of the relay. The timing information
is used to synchronize the relay's internal real-time clock to an accuracy of 1ms in the case
of modulated. The internal clock is then used for the time tagging of the event, fault
maintenance and disturbance records.
2.11.1.1 Second rear communications & InterMiCOM teleprotection board (in P741 & P743)
On ordering this board within a relay, both 2
become connection and setting options. The user may then enable either one, or both, as
demanded by the installation.
There is a hardware option of a second rear communications port, which will run the Courier
language. This can be used over one of three physical links: twisted pair K-Bus (non-polarity
sensitive), twisted pair EIA(RS)485 (connection polarity sensitive) or EIA(RS)232.
SK5: The InterMiCOM board is used to connect to an EIA(RS)232 link, allowing up to eight
programmable signaling bits to be transferred from/to the remote line end relay. A suitable
EIA(RS)232 link must exist between the two line ends, for example a MODEM, or via a
compatible multiplexer (check compatibility before ordering the relay).
The second rear comms. board and Ethernet board are mutually exclusive since they use
the same hardware slot. For this reason two versions of second rear comms. board are
FD
available; one with an IRIG-B input and one without. The physical layout of the second rear
comms. board is shown in Figure .
nd
rear communications and InterMiCOM will
FIGURE 8: REAR COMMS. PORT
Firmware Design
MiCOM P741, P742, P743