Instruction manual

7. FUNCTIONS
IMSRM15-E6
123
(5) Alarm re-hold function
In the alarm hold function, the holding is effective if the input value is in the alarm range at the power
on and is cancelled if the input value will go out of the alarm range. While, in the alarm re-hold
function the hold function becomes effective when the temperature set value is changed again. This
function can be only selected for deviation alarm.
Set value
Alarm
set value
Measured value (PV)
Alarm area
Before the change
of set value
Measured value (PV)
Alarm set value
The change of set value
Alarm area
Set value
A
fter the change o
f
set value
When the measured value (PV) is in the position as shown in the above figure before the change of set
value and then the set value is changed as shown in the figure, the measured value goes into the alarm
area and the alarm is set up. To hold this alarm, the alarm re-hold function can be used effectively.
In the application where the set value is changed continuously by a host computer or a
similar equipment, be careful that alarm is not output if the alarm re-hold function is
selected.
When high alarm with re-hold action is used for alarm function, alarm does not turn
on while hold action is in operation. Use in combination with a high alarm without hold
action in order to prevent overheating which may occur by failure of control devices,
such as welding of relays.
(6) Heater break alarm
The heater break alarm (HBA) function is used to detect the current flowing through the load (heater)
by using a current transformer (CT), to compare the current thus detected to the heater break alarm set
value, and thus to produce a heater break alarm when any of the following causes occurs.
When the heater current does not flow: Heater break or abnormality in the operating unit, etc.
When the control output is on and the current transformer (CT) input value is the HBA set value or
less, the alarm is set up.
When the heater current does not stop: The melting of relay, etc.
When the control output is off and the current transformer (CT) input value is the HBA set value or
more, the alarm is set up.