ITVC Series – Intelligent Total Valve Controller IOM-ITVC-LB-04
DVG AUTOMATION S.p.A.
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4.2
CPU redundancy
Line Break-differential is safety function managed by two independent CPU’s working in parallel, in particular they
manage input reading, logic processing and output enabling.
4.3
Output to drive the SOV
ITVC functions include the test of electrical continuity and absence of short-circuit of coil of SOV. It is described in the
IOM-ITVC-Basic, paragraph “Test of coil of Solenoid Operated Valves” and in the procedures “Coil test” and “Test
coil absorption”, Setup chapter, Administrator menu. Any fault must be detected three consecutive times, before
confirmation.
4.4
Diagnostic
Analogue input diagnostic
The range-ability of the analogue input circuits is from 3 to 21 mA.
CPU’s 1 and 2 perform the following diagnostics:
Under-range
and
Over-range
Both CPU’s assumes that if signal is <3mA or >21mA the transmitter or the acquisition stage is damaged
Action performed:
o
Local “MRT timer” alarm and display of type of fault
o
Switch-over of Monitor relay
o
Exclusion of damaged channel
o
Operation in
1oo1
architecture for a maximum time equal to MRT. Correct system must be restored
(repair or replace the device) or the
configured
LB-d safe action
will be carried out at the end of
MRT time. The menu option
MRT,
in the
Measurement
menu, displays the remaining time before
than MRT time ends
LB-d safe action
will be carried out if the surviving analogue channel fails in the MRT time
Continuous
comparison
and
voting
After A/D conversion, if a single signal deviation is more than 5% compared to the reading of each remaining
signal, both CPU’s assume that:
One of two signals is not reliable, but it is not possible to identify which one
Action performed:
o
LB-d safe action
o
Local alarm and display of type of fault
o
Switch-over of Monitor relay
CPU’s diagnostic
Diagnostics processed by each CPU includes: Diagnostics of comparison between the two CPUs, Software flow
diagnostics, Watchdog, System clock monitor and Detection of a fault not imputable to an identified channel:
o
Power supply diagnostics
o
Temperature diagnostics
o
Comparison diagnostics of redundant channels (1oo2 architecture)
o
CPUs Comparison diagnostic
In case of the above mentioned instances, system switches to safe state.
Summary of Contents for ITVC Series
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