CD Automation Revo M 1PH, User Manual

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CD Automation srl REVO M User’s Manual
REVO_M08
26
14 Heater Break alarm and SCR short circuit (HB Option)
Caution: to work properly the load must be powered at least about 160msec.
The Heater Break circuit read the load resistance with an Internal voltage transducer and Internal
current transformer (C.T.), to calcolate the resistance (V/I).
Minimum current is 10% of the current transformer size.
If load current is below this value the Heater Break Alarm doesn’t work properly.
14.1 Heater break Calibration procedure
An automatic function sets the Heater Break Alarm.
Write in the parameter
   
and
   
If load current decreases for partial or total load failure (sensitivity 20%) HB alarm become ON and
alarm relay change status.
If the unit is still in conduction with no input signal (LED green OFF) it means that there is a short circuit
on thyristors and (SC) become ON.
You can Adjust the sensibility of HB alarm by using the parameter
   
This parameter is setted
between 1 and 255% of the nominal resistance.
This parameter is the maximum reduction of the resistance Load to establish the HB Alarm.
There is also
   
parameter to set a delay to have HB alarm active.
14.2 HB alarm contact (digital output)
The Revo unit with HB option, is supplied with Heater Break alarm contact normally opened (NO):
•
In normal conditions (without alarm) and with auxiliary power supply, the contact to the terminals
has opened (relay coil energized).
•
In alarm condition or without auxiliary power supply the contact to the terminals is closed (relay coil
not energized).
This alarm can be configured in order to activate itself after that one of these alarms occours:
•
HB and SC alarm are active.
•
Only HB alarm is active.
•
Only SC alarm is active.
•
Disable the relay output.