Areva MiCOM P441, Technical Manual

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P44x/EN HW/E33 Relay Description
Page 10/44 MiCOM P441/P442 & P444
CT CT
Buffer
16-bit
ADC
Sample
control
Serial
Interface
16:1
Multiplexer
Up to 5 current inputs
Serial sample data bus
Parallel bus
Parallel bus
Trigger from processor board
Anti-alias filters
Up
to
5
Up
to
5
Up
to
5
Diffn
to
single
Diffn
to
single
Lo
w
pass
filter Lo
w
pass filter
VT VT
3/4 voltage inputs
Transformer board
Input board
4
4
Diffn
to
single
Diffn
to
single
Lo
w
pass
filter Lo
w
pass filter
Calibration
E²PROM
Optical isolator
8 digital inputs
Noise
filter
Optical isolator
P3027ENa
4
Buffer
Noise
filter
FIGURE 2 - MAIN INPUT BOARD
The other function of the input board is to read the state of the signals present on the digital
inputs and present this to the parallel data bus for processing. The input board holds 8
optical isolators for the connection of up to eight digital input signals. The opto-isolators are
used with the digital signals for the same reason as the transformers with the analogue
signals; to isolate the relay’s electronics from the power system environment. A 48V ‘field
voltage’ supply is provided at the back of the relay for use in driving the digital opto-inputs.
The input board provides some hardware filtering of the digital signals to remove unwanted
noise before buffering the signals for reading on the parallel data bus. Depending on the
relay model, more than 8 digital input signals can be accepted by the relay. This is achieved
by the use of an additional opto-board which contains the same provision for 8 isolated
digital inputs as the main input board, but does not contain any of the circuits for analogue
signals which are provided on the main input board.
2.5 Power supply module (including output relays)
The power supply module contains two PCBs, one for the power supply unit itself and the
other for the output relays. The power supply board also contains the input and output
hardware for the rear communication port which provides an RS485 communication
interface.