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Error Detection
The following errors are detected according to status.
Heater layer short errors are detected (overcurrent detection).
The preset overcurrent detection set value is compared with the
heater current and an alarm is output accordingly.
Set value
Current
Alarm
Transistor output models: ALM indicator lit, ALM transistor output
Relay output models: ALM indicator lit, OR of all detection status output
SSR Short Circuit Detection
If current is measured when there is no gate input, an SSR short
circuit error is detected and an alarm is output.
Gate input
Current
measurement
Alarm
Transistor output models: SSR indicator lit, SSR transistor output
Relay output models: SSR indicator lit, OR of all detection status output
SSR Open Circuit Detection
If current is not measured during gate input, an SSR open circuit
error is detected and an alarm is output.
Gate input
Current
measurement
Alarm
Transistor output models: SSR indicator lit, SSR transistor output
Relay output models: SSR indicator lit, OR of all detection status output
Voltage Fluctuation Compensation
The voltage fluctuation compensation function automatically adjusts
the burnout alarm operation level of the K8AC-H depending on
voltage fluctuations in the heater circuit.
The operating value for burnout detection when multiple heaters are
connected is set very close to the normal value. Thus, a false
burnout alarm output will occur if there is a voltage drop in the heater
circuit.
The voltage fluctuation compensation function prevents this type of
false output.
Example: Voltage Drop from 100 V to 95 V in the Heater Circuit
Conditions:
Voltage fluctuation compensation standard value = 100 V
Burnout alarm set value = 10.0 A
If the power supply voltage drops from 100% to 95%, the
operating value will also reduced from 100% to 95%.
Burnout alarm operating value = 10.0 A x 95% = 9.5 A
Gate Input
The gate input provides a sync signal used to link burnout detection
to the control output of the temperature controller.
For SSR control, the voltage output pulse from the temperature
controller is input.
For contactor control, 24 VDC linked to a relay contact of the
temperature controller is input.
For cyclic or phase control, a 4 to 20-mA control signal is input.
If there is no gate input for a Heater Element Burnout Detector, a
heater burnout alarm would be falsely output when the voltage
output pulse from the temperature controller turns OFF, and there
would be no way to tell whether it was a false output.
Note: The gate input function can be disabled. If it is disabled, Heater
Element Burnout Detector operation will not be linked to the
temperature controller control signal. (The gate input can be
used as a simple undercurrent detection relay.)
Power-saving Operation
If there are no key operations performed within a preset time period,
the display automatically turns OFF.
Power Save Mode
Standby Time
Output Operation Time Charts
Heater Burnout and Heater Layer Short (Overcurrent)
Alarms
Heater layer shorts
Overcurrent set value
Heater current
Heater burnout set value
Alarm output
ALM indicator lights. ALM indicator lights.
SSR Short/Open Circuit Alarm
SSR short-circuit
SSR open-circuit
Alarm output
SSR indicator lights. SSR indicator lights.
K8AC-H
Hysteresis
12
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