NR Electric PCS-9611, Instruction Manual

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6 Hardware
PCS-9611 Feeder Relay
6-6
Date: 2014-04-08
6.5 Main CPU Module (NR4106)
The main CPU module is the central part of this equipment, and contains a powerful microchip
processor and some necessary electronic elements. This powerful processor performs all of the
functions for the relay: the protection functions, the communication management functions. There
are several A/D conversion circuits on this module, which are used to convert the AC analog
signals to corresponding DC signals for fulfilling the demand of the electrical level standard. A
high-accuracy clock chip is contained in this module, it provide accurate current time for this relay.
The functional details of the main CPU module are listed as below:

Protection calculations
The main CPU module can calculate protective elements (such as overcurrent element, zero
sequence overcurrent etc.) on the basis of the analog sampled values (voltages and currents)
and binary inputs, and then decides whether the device needs to trip or close.

Communication management
The main CPU module can effectively manage all communication procedures, and reliably
send out some useful information through its various communication interfaces. T hese
interfaces are used to communicate with a SAS or a RTU. It also can communicate with the
human machine interface module. If an event occurs (such as SOE, protective tripping event
etc.), this module will send out the relevant event information through these interfaces, and
make it be easily observed by the user.

Auxiliary calculations
Based on the voltage and current inputs, the main CPU module also can calculate out the
metering values, such as active power, reactive power and power factor etc. All these values
can be sent to a SAS or a RTU through the communication interfaces.

Time Synchronization
This module has a local clock chip and an interface to receive time synchronized signals from
external clock source. These signals include PPS (pulse per second) signal and IRIG -B
signal. Basing on the timing message (from SAS or RTU) and the PPS signal, or basing on
the IRIG-B signal, this module can synchronize local clock with the standard clock.
There are three types of main CPU modules, and the view of the main CPU module is shown in
Figure 6.5-1 .