K8AC-H
2
Compatible with Various Heater Control
Methods
Models with heater burnout alarms for ON/OFF control, phase
control, and cyclic control have been added to the lineup.
Check the current input range, connected CT, and relay output type
before selecting the model from the product specifications.
Note:
Both single-phase and three-phase heaters are supported.
Overcurrent and SSR Failure Detection from
Heater Layer Short Circuits.
•
Overcurrent can be detected from layer short circuits in addition to
providing heater burnout alarms with overcurrent detection
settings.
•
SSR short circuit failures and SSR open circuit failures are
detected by monitoring the heater current and the control outputs
from the temperature controller.
•
Detecting SSR failures enables promptly discovering that
temperature control has failed.
Heater Burnout Alarms for Cyclic Control or
Phase Control Heaters
(K8AC-H
@@
P
@
)
The burnout detection value is shifted according to the
control output value from the temperature controller.
•
Analog control is performed on the output power according to the
temperature controller's current output (4 to 20 mA) when phase
control or cyclic control is used.
•
Heater burnout alarms are stable with the K8AC-H because the
heater burnout alarm values are linked with the control output
value from the temperature controller.
Compatible with Gradient Settings of Power Controllers
When using gradient settings with a power controller, set a gate
current level that is suitable for the gradient settings.
Note:
Set the heater burnout alarm value based on the current at the
heater's rated input.
The transistor output from the K8AC-H2
@@
N
can be used as either an NPN open-collector
output or a PNP equivalent output.
The transistor output of the K8AC-H2
@@
N uses a photocoupler for
isolation with the internal circuits, and so either an NPN open-
collector output or a PNP equivalent output can be used.
Preventive Maintenance
The run time can be measured by the K8AC-H.
Managing the run time history until burnouts occur is useful for
diagnosis and preventative maintenance for equipment.
Count the Total Number of Alarms Output
Set the upper and lower limits to count the total number of alarms that
have been output.
Heater cu
rrent
4 mA
Heater current
Heater burnout
alarm value
7 mA
20 mA
Control output from temperature controller
Heater Burnout Alarm Value
The heater burnout alarm value shifts
according to the control input (4 to
20 mA) from the temperature controller.
Gradient setting: 100%
Gradient setting: 50%
Control signal
0%
100%
Output current
Measurement range
Detected
Not detected
4 mA
14 mA
20 mA
Operation gate current level
NPN Output PNP Equivalent Output
Load
Load power supply
Load power supply
Load
