Update Documentation P44x/EN AD/E44
MiCOM P441, P442 & P444
Page 19/82
This lower value eliminates fleeting pickups that may occur during a battery earth fault, when
stray 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-set
filter of ½ cycle which renders the input immune to induced noise on the wiring: although this
method is secure it can be slow, particularly for intertripping. This can be improved by
switching off the ½ cycle filter in which case one of the following methods to reduce ac noise
should be considered. The first method is to use double pole switching on the input, the
second is to use screened twisted cable on the input circuit.
2.7 Second rear communications board
For relays with Courier, Modbus, IEC60870-5-103 or DNP3 protocol on the first rear
communications port there is the 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.
The second rear comms board and IRIG-B board are mutually exclusive
since they use the
same hardware slot. For this reason two versions of second rear comms board are available;
one with an IRIG-B input and one without. The physical layout of the second rear comms
board is shown in Figure 3.
2.8 Ethernet board
The ethernet board, presently only available for UCA2 communication variant relays,
supports network connections of the following type:
− 10BASE-T
− 10BASE-FL
− 100BASE-TX
− 100BASE-FX
For all copper based network connections an RJ45 style connector is supported. 10Mb fibre
network connections use an ST style connector while 100Mb connections use the SC style
fibre connection.An extra processor, a Motorola PPC, and memory block is fitted to the
ethernet card that is responsible for running all the network related functions such as
TCP/IP/OSI as supplied by VxWorks and the UCA2/MMS server as supplied by Sisco inc.
The extra memory block also holds the UCA2 data model supported by the relay.
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