GE MiCOM P40 Agile Technical Manual

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Contents

P44x/EN FD/Hb6 Firmware Design(FD) 8-12 MiCOM P40 Agile P442, P444Nominalbattery voltage(Vdc)Standard 60% - 80% 50% - 70%No Operation(logic 0) VdcOperation(logic 1) VdcNo Operation(logic 0) VdcOperation(logic 1) Vdc24 / 27 <16.2 >19.2 <12.0 >16.830 / 34 <20.4 >24.0 <15.0 >21.048 / 54 <32.4 >38.4 <24.0 >33.6110 / 125 <75.0 >88.0 <55.0 >77.0220 / 250 <150.0 >176.0 <110 >154Table 1 – Opto inputs threshold levelsThis lower value eliminates fleeting pickups that may occur during a battery earth fault, whenstray capacitance may present up to 50% of battery voltage across an input.Each input also has selectable filtering which can be utilised. This allows use of a pre-setfilter of ½ cycle which renders the input immune to induced noise on the wiring: although thismethod is secure it can be slow, particularly for intertripping. This can be improved byswitching off the ½ cycle filter in which case one of the following methods to reduce ac noiseshould be considered. The first method is to use double pole switching on the input, thesecond is to use screened twisted cable on the input circuit.2.5 Power supply module (including output relays)The power supply module contains two PCBs, one for the power supply unit itself and theother for the output relays. The power supply board also contains the input and outputhardware for the rear communication port which provides an RS485 communicationinterface.2.5.1 Power supply board (including RS485 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 voltagethat will be connected to the relay. The three options are shown in Table 1 below.Nominal dc range Nominal ac range24 – 48 V dc only48 – 110 V 30 – 100 V rms110 – 250 V 100 – 240 V rmsTable 2 - Power supply optionsThe output from all versions of the power supply module are used to provide isolated powersupply rails to all of the other modules within the relay. Three voltage levels are used withinthe relay, 5.1 V for all of the digital circuits, ±16 V for the analogue electronics, e.g. on theinput board, and 22 V for driving the output relay coils. All power supply voltages includingthe 0 V earth line are distributed around the relay via the 64-way ribbon cable. One furthervoltage level is provided by the power supply board which is the 48 V field voltage. This isbrought out to terminals on the back of the relay so that it can be used to drive the opticallyisolated digital inputs.The two other functions provided by the power supply board are the RS485 communicationsinterface and the watchdog contacts for the relay. The RS485 interface is used with therelay’s rear communication port to provide communication using one of either Courier,Modbus or IEC 60870-5-103 protocols. The RS485 hardware supports half-duplexcommunication and provides optical isolation of the serial data being transmitted andreceived.All internal communication of data from the power supply board is conducted via the outputrelay board which is connected to the parallel bus.The watchdog facility provides two output relay contacts, one normally open and onenormally closed which are driven by the processor board. These are provided to give anindication that the relay is in a healthy state.