Pump Relays; Miscellaneous Relays - Siemens SITRANS LUT400 Operating Instructions Manual

General Operation
7.2 Relays
7.2.3.2

Pump relays

If a pump cycle is in progress at the time the fail-safe condition occurs, then the pump cycle
will end prematurely (as if the 'off' setpoints were reached). This has the effect of turning off
all pumps immediately. If a pump run-on occurrence was scheduled for the pump cycle, it will
not occur. However, if a pump run-on occurrence has already begun at the time the fail-safe
condition occurs, then the run-on will complete.
If no pump cycle is in progress at the time the fail-safe condition occurs, then subsequent
pump cycles will not occur (the fail-safe condition will prevent pumps from starting), until the
fail-safe condition is cleared.
7.2.3.3

Miscellaneous relays

External Totalizer relay
If the external totalizer is in the process of recording volume (i.e. the relay is clicking) when a
fail-safe condition occurs, then the current series of clicks will be allowed to complete.
When totalizing volume:
Since pumps do not run when in fail-safe, then the external totalizer will in general not
operate either. If a fail-safe condition occurs during a pump cycle then the volume pumped
for that cycle will not be totalized.
Note
A dedicated alarm exists for fail-safe condition as described above. See Fail-safe Fault
Alarm (Page 102).
When totalizing OCM flow:
The flow totalizers continue to operate during a fail-safe condition, thus the external totalizer
relay will also continue to operate.
External Sampler relay
The External Sampler relay operates the same as the External Totalizer relay described
above. The periodic timeout-click will also continue to occur in fail-safe.
Communications relays
Relays controlled by communications (HART) are not affected by a fail-safe condition.
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Operating Instructions, 07/2019, A5E33329501-AC
SITRANS LUT400