Emergency and Preventive Reactor Protection Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 310

The cabinet consists of: sensors power supply
crates (connected supply blocks and panel com-
puter); signal processing crates; two relay output
crates; power supply crates.
In the signal processing crate data entry blocks
are structurally and electrically connected, they
provide:

• Signal receiving, received data processing,

control of set conditions for emergency and
preventative protection actuation (1);

• Forming (in accordance with the regi-

mented network protocol) of digital mes-
sages, containing data received from input
blocks, as well as identiiers of protection
actuation conditions, if these conditions
were detected (2); • Input and normalization of discrete signals;

• Input and conversion of continuous direct-
current signals;
• Input and conversion thermoelectric con-
verters natural signals;
• Processing of the received data and form-
ing of control signals (commands);
• Monitoring of technical state and diagnos-
tics of cabinet, transmission lines and adja-
cent equipment failures.

• Conversion of digital messages electrical

elements into optical (3) and transition of
messages via iber-optical communication
lines to protection signals forming blocks
in two other channels (signals forming
cabinets);

• Receiving of similar messages from pro-

tection signals forming blocks of two other
channels, conversion of optical elements
into electrical (4) and decoding of the re-
ceived digital messages in accordance with
the regimented network protocol (5);

Protection signals forming block performs
(numerical symbols in brackets correspond to
symbols at the respective schemes in Figure 3): • Comparison of messages received from

input blocks and from two other channels,
detection of discrepancies, forming and

Figure 3. Structure scheme of signals forming cabinet (1-st set, channel 2)