Monitoring Functions; Measurement Supervision; General; Hardware Monitoring - Siemens siprotec SJ62 User Manual

2 Functions
2.11

Monitoring Functions

2.11.1 Measurement Supervision

2.11.1.1 General

2.11.1.2 Hardware Monitoring

Auxiliary and Refer-
ence Voltages
Buffer Battery
Memory Compo-
nents
185
The device is equipped with extensive monitoring capabilities - both for hardware and
software. In addition, the measured values are also constantly monitored for plausibil-
ity, therefore, the current transformer and voltage transformer circuits are largely inte-
grated into the monitoring.
The device monitoring extends from the measuring inputs to the binary outputs. Mon-
itoring checks the hardware for malfunctions and impermissible conditions.
Hardware and software monitoring described in the following are enabled continuous-
ly. Settings (including the possibility to activate and deactivate the monitoring function)
refer to monitoring of external transformers circuits.
The processor voltage of 5 VDC is monitored by the hardware since if it goes below
the minimum value, the processor is no longer functional. The device is under such a
circumstance removed from operation. When the supply voltage returns, the proces-
sor system is restarted.
Failure of or switching off the supply voltage removes the device from operation and
a message is immediately generated by a normally closed contact. Brief auxiliary
voltage interruptions of less than 50 ms do not disturb the readiness of the device (for
nominal auxiliary voltage > 110 VDC).
The processor monitors the offset and reference voltage of the ADC (analog-digital
converter). The protection is suspended if the voltages deviate outside an allowable
range, and lengthy deviations are reported.
The buffer battery, which ensures operation of the internal clock and storage of
counters and messages if the auxiliary voltage fails, is periodically checked for charge
status. If it is less than an allowed minimum voltage, then the „Fail Battery"
message is issued.
All working memories (RAMs) are checked during start-up. If a fault occurs, the start
is aborted and an LED starts flashing. During operation the memories are checked
with the help of their checksum. For the program memory, the cross sum is formed
cyclically and compared to the stored program cross sum.
For the settings memory, the cross sum is formed cyclically and compared to the cross
sum that is freshly generated each time a setting process takes place.
If a fault occurs the processor system is restarted.
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015