Omron K8AC-H Series User manual

CSM_K8AC-H_DS_E_5_1
1
Digital Heater Element Burnout Detector
K8AC-H
A high-precision Heater Element Burnout
Detector compatible with a wide-range of
heater control methods.
• Compatible with contactor, SSR, cyclic control, and phase
control methods.
• Compatible with a wide range of heater capacities, from 0.200 to
200.0 A AC (range covered by 3 models)
• Voltage fluctuation compensation function enables accurate
heater burnout detection, because power supply voltage
fluctuations resulting in heater current fluctuation will not cause
faulty outputs.
• Detects burnouts for even one heater when using multiple
heaters.
• If the gate function is disabled, the gate input can be used as an
undercurrent/overcurrent relay or for motor or lamp loads (2
circuits).
•CEMarking.
• Contributes to preventative maintenance for heater burnout.
Note: Consult with your OMRON representative before using phase and
cyclic control under the following conditions.
•Using multiple heaters with different heater capacities
•Using heaters with varying heater resistance (e.g., halogen
heaters)
Features
Compatible with Many Heater Control
Methods
The K8AC-H detects burnouts for cyclic and phase control heaters,
which could not be detected by the K2CU.
One Digital Heater Element Burnout Detector can handle single-
phase or three-phase heaters.
Applicable to Wide Current Range
Current can be measured between 0.200 and 200.0 A using an
external current transformer.
Monitors Heater Current
The heater current can be checked on the main display. Error status,
such as that for heater burnout alarms, can also be displayed on the
character display.
Voltage Fluctuation Compensation
Function
The voltage fluctuation compensation function enables accurate
heater burnout detection, because power supply voltage fluctuations
resulting in heater current fluctuation will not cause faulty outputs.
This function is required when detecting minor current fluctuations.
High-precision Heater Burnout
Detection
Digital settings enable high-precision heater burnout detection.
High-precision threshold value setting is possible using current
measurement value display.
Type ON/OFF control
(connector/SSR)
Cyclic
control
Phase
control
Item K8AC-H@@C@-FLK K8AC-H@@P@-FLK
Single-phase heater {{{{
Three-phase heater {{{{
Model K8AC-H11@K8AC-H12@K8AC-H13@
Item
Current
measurement range 0.200 to 2.200 A AC 2.00 to 22.00 A AC 20.0 to 200.0 A AC
Appropriate Current
Transformer model K8AC-CT20S
K8AC-CT20L
K8AC-CT20S
K8AC-CT20L
K8AC-CT200
K8AC-CT200L
Main display
Measurement values
·Heater current
·Power supply voltage
Error display
·Heater burnout detection
·Overcurrent detection
·SSR short circuit detection
·SSR open circuit detection

K8AC-H
2
SSR Short Circuit Detection
Quickly detects control failures caused by SSR short circuits.
Useful for preventing shipping of faulty products and for improving
productivity.
Detects Overcurrents in Heater Circuits
Detects overcurrents from heater layer shorts and outputs an alarm.
Useful for preventing SSR deterioration caused by overcurrents.
RS-485 Communications
Measurement data, such as the present heater current, maximum/
minimum heater current, and power supply voltage, can be read
using RS-485 communications.
The current when the heater burned out and the total operating time
are recorded in memory, and this data can be used for preventative
equipment maintenance. (This data can be checked on the main
display.)
CE Marking
Compact Unit
(35 ×90 ×100 mm (W ×H ×D))
Problems with Current Heater Element
Burnout Detectors
•K2CU Heater Element Burnout Detectors could not detect burnouts
with cyclic or phase control heaters (performed unnecessary
operations). Generally, heater burnouts could not be detected even
by the heater burnout detection function of power regulators (phase
control devices) when multiple heaters were connected. Also,
burnout detection was not accurate when temperature controller
outputs were small.
•Power voltage fluctuations in the heater circuit caused current
fluctuations. Without a voltage fluctuation compensation function,
voltage fluctuations cause unnecessary operation.
•The K2CU has a narrow rated current range and cannot detect
minute current fluctuations when multiple heaters are detected due
to the low resolution.
Differences from Other Current Heater
Element Burnout Detection Functions
: Can detect with high precision {: Can detect ×: Cannot detect
Model Number Structure
■Model Number Legend
1. Basic Model
K8AC-H: Digital Heater Element Burnout Detector
2. Product Type
1: Series number
3. Current Input Range
1: 0.200 to 2.200 A
2: 2.00 to 22.00 A
3: 20.0 to 200.0 A
4. Heater Control Type
C: ON/OFF control (SSR or contactor)
P: Phase control or cyclic control
5. Output Type
C: Relay contact output (one SPDT relay contact output)
T: Transistor output (two NPN open collector outputs)
6. Communications Specifications
FLK: RS-485
7. Power Supply Voltage
100-240VAC: 100 to 240 VAC
Classification Heater Element
Burnout
Detector
Tempera-
ture con-
troller
Power
regula-
tor (thy-
ristor)
Item K8AC-H K2CU
Heater
burnout
detection
Single-
phase heater {{ { {
Three-phase
heater {{ { {
Contactor
control
heater
{{ { {
SSR control
heater {{ { {
Phase
control
heater
×× {
Cyclic
control
heater
×× ×
Voltage fluctuation
compensation function { ××
SSR short circuit
detection function {×{×
Overcurrent detection
function {×× {
12345 6 7
K8AC-H1 @@@ -FLK 100-240VAC

K8AC-H
3
Ordering Information
■Digital Heater Element Burnout Detectors
Note: Consult with your OMRON representative if multiple heaters are connected in parallel with different heater capacities, or if a heater with
varying heater resistance is used.
■Optional Products (Sold Separately)
Current Transformers
Note: When selecting a current transformer, ensure that the rated current of the heater does not exceed the rated current of the transformer.
Heater control method Input specifications Output specifications Current input range Model
Contactor control
SSR control Two current inputs (single-/three-phase) One relay output + RS-485 0.200 to 2.200 A K8AC-H11CC-FLK
2.00 to 22.00 A K8AC-H12CC-FLK
20.0 to 200.0 A K8AC-H13CC-FLK
Two transistor outputs + RS-485 0.200 to 2.200 A K8AC-H11CT-FLK
2.00 to 22.00 A K8AC-H12CT-FLK
20.0 to 200.0 A K8AC-H13CT-FLK
Phase control (cyclic control) One relay output + RS-485 0.200 to 2.200 A K8AC-H11PC-FLK
2.00 to 22.00 A K8AC-H12PC-FLK
20.0 to 200.0 A K8AC-H13PC-FLK
Two transistor outputs + RS-485 0.200 to 2.200 A K8AC-H11PT-FLK
2.00 to 22.00 A K8AC-H12PT-FLK
20.0 to 200.0 A K8AC-H13PT-FLK
Through-hole diameter Rated current Installation method Model
5.8 mm dia. 0.200 to 22.00 A Surface-mounted with screws K8AC-CT20S
12 mm dia. Rear-surface mounted with screws
Binding band K8AC-CT20L
20.0 to 200.0 A Rear-surface mounted with screws
Binding band K8AC-CT200
30 mm dia. 20.0 to 200.0 A Surface-mounted with screws K8AC-CT200L

K8AC-H
4
Specifications
■Ratings
Note: 1. The gate input enables correct measurement by syncing to heater control. When using it with contactor ON/OFF control, receive the relay
contact output from the temperature controller or other controller with an auxiliary relay and then use this signal as the gate input signal
to the K8AC-H. The gate function can also be disabled. If it is disabled, the gate input can be used as a normal undercurrent/overcurrent
relay.
2. When using the K8AC-H for a 380 to 480-V AC power supply circuit, Use a 2:1 step-down transformer that can supply at least 10 VA to
the load.
3. Order the CTs separately.
Power supply voltage 100 to 240 VAC (50/60 Hz) (See note 2.)
Operating voltage range 85% to 110% min. of the rated power supply voltage (85 to 264 V)
Power consumption
(at max. load)
35 VA max. (at max. load)
Applicable circuits Single-phase or three-phase (with same model)
Applicable control methods Contactor ON/OFF control (e.g., temperature controller with relay output)
SSR control (e.g., temperature controller with voltage output)
Cyclic control and phase control (e.g., temperature controller with current output)
Current measurement Current measurement via two special CTs (Burnout alarm set value can be set separately for each CT.)
Measurement method Average value calculation
Gate input
signal
(See note 1.)
Contactor ON/OFF
control
Voltage = 12/24 VDC (continuous input possible to 30 VDC)
Input impedance = 4 kΩmin.
SSR control ON voltage: 9.6 VDC max., OFF voltage: 1 VDC min.
Minimum voltage pulse ON time for burnout detection: 200 ms min.
Cyclic and phase
control
4 to 20 mA DC (Burnout detection is possible for an input of 7 mA or greater.)
Input impedance = 50 Ωmax.
Output Relay contact
output:
K8AC-H@@@C-FLK
One SPDT relay contact output
Same output used for heater burnout alarms, overcurrent alarms, SSR short circuit alarms, and SSR open
circuit alarms.
0.3 A at 125 VAC (resistive load), 1 A at 30 VDC (resistive load)
Maximum switching capacity: 37.5 VA, 30 W
Mechanical durability: 50 million operations min., electrical durability: 100,000 operations min.
Transistor output:
K8AC-H@@@T-FLK
Two NPN open-collector outputs
One ALM output: Outputs heater burnout alarms and overcurrent alarms
One SSR error output: Outputs SSR short circuit and open circuit alarms.
12 to 24 VDC, 50 mA max.
OFF leakage current: 100 μA max., ON residual voltage: 1.5 V max.
Communications RS-485 1200, 2400, 4800, 9600, 19200 bps (CompoWay/F)
Indication method 7-segment digital display: No. of display digits: 4 (red)
LED status indicators: RUN (green), ADJ (orange), SET (orange), GATE (orange), SSR (orange) and ALM
(orange)
Main functions Heater burnout alarms, overcurrent alarms, SSR short circuit alarms, SSR open circuit alarms, voltage
fluctuation compensation, output ON delay timer, energy-saving mode, key protection, and power supply
voltage measurement
Ambient operating temperature −10 to +55°C (with no icing or condensation)
Ambient operating humidity 25% to 85% (with no condensation)
Storage temperature −25 to +65°C (with no icing or condensation)
Altitude 2,000 m max.
Dimensions 35 ×90 ×100 mm (W x L x H)
Case material PC (Polycarbonate)
Case color Munsell N1.5
Mounting method Mounting to a DIN Track
Special CT models (See note 3.) Current input range Applicable models
K8AC-CT20S 0.200 to 2.200 A
2.00 to 22.00 A
K8AC-H@1@@, K8AC-H@2@@
K8AC-CT20L
K8AC-CT200 20.0 to 200.0 A K8AC-H@3@@
K8AC-CT200L 20.0 to 200.0 A K8AC-H@3@@

K8AC-H
5
■Characteristics
Note: 1. Current Transformers are sold separately.
2. The values for measurement current apply to combined use with a specialized Current Transformer.
Item
Model Models for contactor control and SSR control
K8AC-H@@@C@-FLK
Models for phase control and cycle control
K8AC-H@@P@-FLK
Heater
current input
(at 10 to 30°C)
category II
Input range K8AC-H@1@@: 0.200 to 2.200 A (Current Transformer: K8AC-CT20S (5.8 dia.), K8AC-CT20L (12 dia.)
(See note 1.))
K8AC-H@2@@: 2.00 to 22.00 A (Current Transformer: K8AC-CT20S (5.8 dia.), K8AC-CT20L (12 dia.)
(See note 1.))
K8AC-H@3@@: 20.0 to 200.0 A (Current Transformer: K8AC-CT200 (12 dia.), K8AC-CT200L (30 dia.)
(See note 1.))
Measurement
accuracy
±3% rdg ±10 digits max. (See note 2.) ±6% rdg ±10 digits max. (at control level of 100%)
(See note 2.)
Vol tage
fluctuation
compensation
category II
Input range 85 to 264 VAC
Measurement
accuracy
±3% rdg ±10 digits max.
Gate input Input range 0 to12 VDC or 0 to 24 VDC
ON: 9.6 VDC max., OFF: 1 VDC min.
4 to 20 mA DC
Display cycle Selectable: Immediate, 0.2 s, 0.5 s, 1.0 s
Output ON-delay time 0.0 to 99.9 s (operating time)
Soft start time 0.0 to 99.9 s (Used when using the soft start function of a Power Controller)
Output reset method Automatic reset
Output hysteresis 1 to 999 digits
Output response time 500 ms max. 3.5 s max.
Insulation resistance 20 MΩmin. (at 500 VDC) between external terminals and case
Dielectric strength 2,000 V for 1 min between the external terminals and the case
Noise immunity Power supply terminals normal/common mode: ±1,500 V (startup 1-ns square-wave noise, pulse width:
1 μs/100 ns)
Vibration resistance Vibration: 10 to 55 Hz, Acceleration: 50 m/s2for 5 min with 10 sweeps each in X, Y, and Z directions
Shock resistance 150 m/s2 (100 m/s2for relay contacts) 3 times in 6 directions in X, Y, and Z directions
Maximum
allowable
input
Current Transformer
primary-side current
K8AC-H@1@@: 4 A: 30 s, 12 A: 1 s
K8AC-H@2@@: 40 A: 30 s, 120 A: 1 s
K8AC-H@3@@: 400 A: 30 s, 1200 A: 1 s
Gate input: 4 to 20 m 40 mA DC continuous
Voltage pulse gate
input
30 VDC continuous
Input
impedance
Gate input: 4 to 20 m 50 Ωmax.
Voltage pulse gate
input
4 kΩmax.
Weight Approx. 200 g
Memory protection Non-volatile memory (number of writes: 100,000 operations)
Installation environment Installation Category 2, Pollution Class 2
Approved standards EN 61010-1 (IEC 61010-1) (TÜV evaluation)
EMC EMI: EN61326 Industrial applications
Radiated Interference Electromagnetic Field Strength: EN55011 Group 1, class A
Noise Terminal Voltage: EN55011 Group 1, class A
EMS: EN61326 Industrial applications
ESD Immunity: EN61000-4-2: 4 kV (contact discharge)
8 kV (air discharge)
Electromagnetic Immunity: EN61000-4-3: 10 V/m 1 kHz sine wave amplitude modulation
(80 MHz to 1 GHz)
Fast Transient Burst Immunity: EN61000-4-4: 2 kV (power line)
1 kV (I/O signal line)
Surge immunity: EN61000-4-5: 1 kV (line to line, power line)
2 kV (line to ground, power line)
Conducted Noise Immunity EN61000-4-6: 3 V (0.15 to 80 MHz)
Voltage Dip/Interrupting Immunity EN61000-4-11: 0.5 cycle, 0.180°,100% (rated voltage)

K8AC-H
6
■I/O Ratings
Relay Contact Output
Transistor Output
Communications Specifications
Item Load Resistive load (cosφ= 1)
Rated load 125 VAC, 0.3 A, 30 VDC, 1 A
Maximum contact
voltage
125 VAC, 60 VDC
Maximum contact
current
1 A
Maximum switching
capacity
37.5 VA, 30 W
Minimum applicable load
(failure rate P value,
reference value)
5 VDC, 10 mV
Mechanical life
expectancy
50,000,000 operations min. (at a
switching frequency of 18,000 times/h)
Electrical life expectancy
(Ambient temperature
condition: 20°C)
100,000 operations min. (at rated load
and switching frequency of 1,800 times/
h)
Maximum load voltage 12 to 24 VDC (+10%, −15%)
Maximum load current 50 mA
OFF leakage current 100 µA max.
ON residual voltage 1.5 V max.
Item Communica-
tions
RS-485
Transmission method Two-wire, half-duplex
Synchronization method Start-stop synchronization
Baud rate 1,200, 2,400, 4,800, 9,600, or 19,200
bps
Transmission code ASCII

K8AC-H
7
Connections
■Terminal Arrangement
Note: 1. Terminals 4 to 6: Alarm output terminals. Depend on the
output type (relay output or transistor outputs).
2. Terminals 11 and 12: Gate input terminals. Depend on the
heater control type (contactor/SSR control or cyclic/phase
control).
■Current Input Circuits
CT Inputs (Heater Current)
■Output Circuits
Open Collector Outputs Contact Outputs
Note: For contact outputs, the same outputs are used for SSR error
and for heater burnouts and heater layer shorts alarm outputs.
7
CT1 CT2 Linear current
DC 4 to 20 mA RS-485
8910
7 8 910 11 12 13 14
11
Voltage pulses
0 to 12 VDC or
0 to 24 VDC
12
H8AC-H1@C@
Gate input
H8AC-H1@P@
+−
11 12
+−
13 14
CommunicationsCurrent inputs
1 2
Operating power supply
100 to 240 VAC
A(−)B(+)
COM COM
125 VAC,
AC 0.2 A
30 VDC,
DC 1 A
12 to 24 VDC,
DC 50 mA
456456
Outputs
H8AC-H1@@T H8AC-H1@@C
12 3 4 5 6
Terminals Name Description Applicable
models
1 to 2 Operating
power
supply
Connect to the operating
power supply.
All models
5 to 4,
6 to 4
Outputs Outputs SSR open or short
circuit detection results.
Outputs heater burnout or
overcurrent detection
results.
K8AC-H1@@T
(transistor
outputs)
5, 6 to 4 Outputs an OR of the status
of all alarms.
K8AC-H1@@C
(relay output)
7 to 8 Current
inputs
Connect to CT1. Current
input from CT1 secondary-
side output.
All models
9 to 10 Connect to CT2. Current
input from CT2 secondary-
side output.
11 to 12 Gate input Connect to gate signal
(voltage pulse).
K8AC-H1@C@
Connect to a 4 to 20-mA
gate signal.
K8AC-H1@P@
13 to 14 Commu-
nications
Connect to host device for
RS-485 communications.
All models
CT2
CT1
7
8
9
10
A/D
conversion
−
+A/D
conversion
−
+
4
5
6
Transistor
drive circuit
Transistor
drive circuit
COM
SSR alarm output
Heater burnout, heater layer short,
overcurrent alarm output
4
5
6
Relay
drive circuit
COM
N.C. contact
N.O. contact
+12 V

K8AC-H
8
■External Connection Example
Wiring Method When Using the K8AC-H with SSR Control Heaters
Wiring Method When Using the K8AC-H with Contactor Control Heaters
Operation Description
•If the heater current detected at either CT1 or CT2 falls
below the burnout alarm set value, an alarm is output. The
burnout alarm set value can be set separately for CT1 and
CT2.
No burnout alarm is output, however, when the
temperature controller control output is OFF.
Burnouts are detected only while the temperature
controller control output is being input to the gate input
terminals (11 and 12).
Faulty outputs do not occur because heater burnout
detection is linked with the temperature controller.
•The minimum burnout detection time is 200 ms. Shorter
burnouts are not detected.
•Turn ON the voltage fluctuation compensation function
(default = OFF) to detect power supply voltage fluctuations
and automatically adjust the burnout alarm levels to
compensate. Also, turn ON the voltage fluctuation
compensation function to detect minor current fluctuations.
Correct Usage
•Always take the control power supply from the primary
side of the SSR.
•Use temperature controllers with a 12 or 24-VDC voltage
output (30 VDC max.).
•CT1 and CT2 are special products. Use the K8AC-CT@@.
•The CTs do not have polarity.
•Connect only one CT for single-phase heaters.
Connect two CTs for three-phase heaters.
•For three-phase heaters, always set the burnout alarm set
values for both CT1 and CT2.
Operation Description
•If the heater current detected at either CT1 or CT2 falls
below the burnout alarm set value, an alarm is output. The
burnout alarm set value can be set separately for CT1 and
CT2.
No burnout alarm is output, however, when the
temperature controller control output is OFF.
Burnouts are detected only while the temperature
controller control output is being input to the gate input
terminals (11 and 12).
Faulty outputs do not occur because heater burnout
detection is linked with the temperature controller.
•The minimum burnout detection time is 200 ms. Shorter
burnouts are not detected.
•Turn ON the voltage fluctuation compensation function
(default = OFF) to detect power supply voltage fluctuations
and automatically adjust the burnout alarm levels to
compensate. Also, turn ON the voltage fluctuation
compensation function to detect minor current fluctuations.
Correct Usage
•Always take the control power supply from the primary
side of the contactor.
•Use a temperature controller with relay output.
•The input to the gate input terminals (11 and 12) must
be a DC voltage input, so wire the 24-VDC power
supply as shown in the diagram to the left.
•CT1 and CT2 are special products. Use K8AC-CT@@.
•The CTs do not have polarity.
•Connect only one CT for single-phase heaters.
Connect two CTs for three-phase heaters.
•For three-phase heaters, always set the burnout alarm set
values for both CT1 and CT2.
Heater
Power supply
SSR
CT2
CT1
Temperature
Controller
(DC voltage output)
4
3
5
6
78 910 1112
13 1412
RS-485 communications
4
5
6
For transistor output
Heater
Power supply
Contactor
CT2
CT1
Temperature
Controller
(relay output)
24-VDC
power supply
3
78 910 1112
13 1412
RS-485 communications
4
5
6
For transistor output
X
4
5
6

K8AC-H
9
Wiring Method When Using the K8AC-H with Cyclic Control Heaters
Wiring Method When Using the K8AC-H with Phase Control Heaters
Operation Description
•If the heater current detected at either CT1 or CT2
falls below the burnout alarm set value, an alarm is
output. The burnout alarm set value can be set
separately for CT1 and CT2.
No burnout alarm is output, however, when the
temperature controller control output is OFF.
Burnouts are detected only while the temperature
controller control output is being input to the gate input
terminals (11 and 12).
Burnout is detected with no errors because the
automatic adjustment of burnout alarm level is linked
to the temperature controller control output (4 to
20 mA).
•Burnout is detected when control outputs from the
temperature controller are 7 mA min.
Correct Usage
•Always take the control power supply from the primary
side of the SSR.
•Use a temperature controller with a 4 to 20-mA current
output.
•Always adjust the burnout alarm set value when the
temperature controller's control output is at 100%
(20 mA).
The value at 100% output is used as a reference for
adjusting burnout alarm levels to compensate for
inputs between 4 and 20 mA.
•CT1 and CT2 are special products. Use K8AC-CT@@.
•The CTs do not have polarity.
•Connect only one CT for single-phase heaters.
Connect two CTs for three-phase heaters.
•For three-phase heaters, always set the burnout alarm
set values for both CT1 and CT2.
Operation Description
•If the heater current detected at either CT1 or CT2
falls below the burnout alarm set value, an alarm is
output. The burnout alarm set value can be set
separately for CT1 and CT2.
No burnout alarm is output, however, when the
temperature controller control output is OFF.
Burnouts are detected only while the temperature
controller control output is being input to the gate input
terminals (11 and 12).
Burnout is detected with no errors because the
automatic adjustment of burnout alarm level is linked
to the temperature controller control output (4 to
20 mA).
•Burnout is detected when control outputs from the
temperature controller are 7 mA min.
Correct Usage
•Always take the control power supply from the primary
side of the Power Controller.
•Use a temperature controller with a 4 to 20-mA current
output.
•Always adjust the burnout alarm set value when the
temperature controller's control output is at 100% (20 mA).
The value at 100% output is used as a reference for
adjusting burnout alarm levels to compensate for inputs
between 4 and 20 mA.
•Adjust the burnout alarm set value at a 100% output for
gradient settings as well.
•If using the soft startup function with a power regulator, set
the soft startup function on the K8AC-H as well, to prevent
malfunctions.
•CT1 and CT2 are special products. Use K8AC-CT@@.
•The CTs do not have polarity.
•Connect only one CT for single-phase heaters.
Connect two CTs for three-phase heaters.
•For three-phase heaters, always set the burnout alarm set
values for both CT1 and CT2.
•When using the power regulator's gradient settings,
change the operation gate current level so that the heater
current value is within the measurement range. (The initial
value is 7 mA.)
For details on operating methods, refer to pages 18 to 19.
Heater
(See note.)
Power supply
SSR SSR
CT2
CT1
G32A-EA
Cyclic
Control Unit
Temperature
Controller
4 to 20 mA current output
3
78 910 11
12
13 1412
RS-485 communications
4
5
6
For transistor output
4
5
6
Note: Consult with your OMRON representative if multiple heaters
are connected in parallel different heater capacities, or if a
heater with varying heater resistance is used.
Heater
(See note.)
Power supply
Power
Regulator
CT2
CT1
Temperature
Controller
4 to 20 mA current output
3
78 910 1112
13 1412
RS-485 communications
4
5
6
For transistor outputs
4
5
6
Note: Consult with your OMRON representative if multiple heaters
are connected in parallel different heater capacities, or if a
heater with varying heater resistance is used.

K8AC-H
10
■Heater Connection Methods and Current
Depending on the heater connection method, the current when an error occurs will be as shown in the following table. Refer to this table when
determining burnout alarm set values.
Note: This is the current for when a 200-V, 1-kW heater is used for single-phase or three-phase operation.
Normal condition Abnormal condition
Single-phase
Three-
phase
Delta
connection
Star
connection
V
connection
200 V
5 A
5 A
1 kW
0 A
0 A
200 V
200 V
200 V
1 kW
1 kW
1 kW
8.7 A
8.7 A
8.7 A
200 V
(5 A ×3 )
7.5 A
7.5 A
)
2
3
(5 A ×3 ×
5 A
5 A
8.7 A
)
3
1
(5 A ×3 ×
200 V
200 V
1kW
1 kW
1 kW
2.9 A
2.9 A
2.9 A
200 V
)
3
1
(5 A ×
2.5 A
2.5 A
)
2
3
(5 A ×3
1×
2.5 A
2.5 A
)
2
3
(5 A ×3
1×
200 V
200 V
1 kW
1 kW
5 A
8.7 A
5 A
200 V
(5 A ×3 = 8.7 A) 1
2.5 A
2.5 A
(5 A ×)
2(5 A ×1)
5 A
5 A

K8AC-H
11
■Rate of Change for Currents with Parallel Heaters
The following table shows the current change ratios when multiple heaters of the same capacity are connected in parallel and one of the heater
elements burns out. Use this table for reference when making corrections.
If five single-phase heaters are connected in parallel, the current change when burnout occurs is 20% per heater.
If the current for a single heater is low and the change ratio is very slight, it may not be detected. Therefore take into account the detection accuracy
for the total current when selecting the number of heaters to be connected in parallel.
Note: 1. The figures in the above table show the current change ratios when burnout occurs for one heater connected in parallel.
2. The numbers represent the current ratio after one heater burns out, with the current prior to the burnout (i.e., the normal current) taken
as 1.
3. In actual operation there may be effects from factors such as load (heater) imbalances, so conduct an actual test for confirmation before
making adjustments if the current change ratio between normal and abnormal operation is slight.
4. Consult with your OMRON representative if multiple heaters are used with different heater capacities.
Operation
■Main K8AC-H Functions
The K8AC-H is a digital heater burnout detector that detects heater
burnout by measuring the heater current from various power supply
systems.
The K8AC-H provides the following functions.
Applicable Heater Control Methods
The following heater control methods can be used.
ON/OFF Control (Contactor/SSR)
Cyclic Control
Phase Control (Applicable to 4 to 20 mA Current-output
temperature controllers)
Heater Burnout Alarm
The preset burnout detection value is compared with the heater
current and an alarm is output accordingly.
Connection n=1 n=2 n=3 n=4 n=5
Single-
phase
With one heater
burned out, I is 0.
0.5 0.67 0.75 0.8
Star
connection
Current in
burned-out
phase
With one heater
burned out, I is 0.
0.6 0.75 0.82 0.86
Current in other
phases
0.87 0.92 0.95 0.96 0.97
Delta
connection
Current in lines
near burned-out
phase (Same as
2-phase.)
0.58 0.77 0.84 0.88 0.91
Current in other
phases
11111
n heaters
I
INumber of
heaters per
phase = n
I
Number of heaters
per phase = n
ON
1 to 99 s
OFF
ON
0.2 s
OFF
ON
Half-cycle
OFF
500 ms 100 ms
Current
Set value
Alarm
Transistor output models: ALM indicator lit, ALM transistor output
Relay output models: ALM indicator lit, OR of all detection status output

K8AC-H
12
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.
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.
SSR Open Circuit Detection
If current is not measured during gate input, an SSR open circuit
error is detected and an alarm is 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.
Output Operation Time Charts
Heater Burnout and Heater Layer Short (Overcurrent)
Alarms
SSR Short/Open Circuit Alarm
Transistor output models: ALM indicator lit, ALM transistor output
Relay output models: ALM indicator lit, OR of all detection status output
Set value
Current
Alarm
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
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
Power Save Mode
Standby Time
Heater burnout set value
Heater current
Hysteresis
Heater layer shorts
Overcurrent set value
ALM indicator lights. ALM indicator lights.
Alarm output
SSR open-circuit
SSR indicator lights. SSR indicator lights.
Alarm output
SSR short-circuit

K8AC-H
13
Using the Power Regulator's Gradient
Settings
The power regulator's gradient settings can be used to prevent
malfunction by setting the operation gate current level. The
relationship between the gradient settings and output current
depends on the power regulator manufacturer and model, so be sure
to check the characteristics of the power regulator being used before
setting.
Setting Example
Initial setting: 7 mA
When the power regulator's gradient settings are changed, the
operation gate current level is set so that the output current is within
the measurement range. (In the following diagram, 14 mA is set.)
Using Halogen or Other Heaters with
Varying Resistance during Phase and
Cyclic Control
When phase control is used with halogen heaters or other pure metal
heaters, the heater resistance fluctuates according to the control
level. As a result, high-precision detection of heater burnout is not
possible. The effect on the heater and setting methods depends on
the heater being used. Therefore, consult with your OMRON
representative before using a heater with varying resistance values.
Halogen Heater Resistance Fluctuation
Example
In the following example, burnout of one element in a six-element
heater can be detected at a control level of 20 mA, but detection is
not possible due to the effect of fluctuating resistance if the control
level is any lower.
4 mA
0%
100%
7 mA 20 mA
Output current
Measurement range
Gradient
setting 100%
Control signal
Not detected Detected
4 mA 14 mA 20 mA
0%
100%
Output current
Measurement range
Gradient
setting 100%
Gradient
setting 50%
Control signal
Not detected Detected
7 mA 20 mA4 mA
0 Ω
2 Ω
4 Ω
6 Ω
8 Ω
Heater resistance
Detectable range
Three elements
burned out
One element
burned out
Threshold
Normal
(six elements in parallel)
Control signal

K8AC-H
14
Nomenclature
■Nomenclature and Operations
Note: Check the specific status using the alarm display parameters
on the main display.
Alarm Indicators
Note: 1. As soon as the cause of an alarm is removed, the alarm is
reset automatically.
2. If multiple alarms occur simultaneously, the one with the
highest priority is displayed.
3. If the mode is changed to ADJ or SET mode while an alarm
is in effect, the alarm output is reset and the ALM and SSR
indicators turn OFF.
Processing Value Display Ranges and
Functions
Note: 1. The decimal point position depends on the input type.
K8AC-H@1@@: 0.100 to 2.300
K8AC-H@2@@: 1.00 to 23.00
K8AC-H@3@@: 10.0 to 230.0
2. If the display is below 0100, the bar display “----” will be
shown.
Operation indicators
Main display area
Shift key
Up key
Down key Mode key
Level key
Name Operation
Main display Displays processing values, parameter characters,
and set values.
Oper-
ation
indi-
cators
RUN (Mea-
surement
operation)
Lights when the power is turned ON and the
measurement operation is in progress.
OFF at all other times.
ADJ
(Adjust)
Lights while in adjust mode.
Flashes while in test mode.
OFF at all other times.
SET (Set) Lights while in set mode.
OFF at all other times.
GATE
(Gate)
Lights or turns OFF according to gate input status.
Gate pulse: Lights for high voltage pulse; OFF for
low voltage pulse.
Gate linear: Lights for 4 mA or over; OFF for less
than 4 mA.
SSR
(SSR error)
(See note.)
Lights when an SSR error occurs (open or short
circuit).
OFF when SSR is normal.
ALM
(Alarm)
(See note.)
Lights for heater burnout or overcurrent.
OFF at all other times.
Up key Increments a set value when the set value is in
change status.
Down key Decrements a set value when the set value is in
change status.
Shift key Used to check set values while parameters are
displayed, and to put set values in change status.
Used to shift the set value digit when the set value is
in change status.
Mode key Used to switch the displayed parameter.
Level key Used to change the level.
Order of
priority
Alarm 7-segment
display
characters
LED
indicator
Alarm contents
1 Heater burnout 1 hbt1 ALM
indicator lit CT1 heater burnout detected.
2 Heater burnout 2 hbt2 ALM
indicator lit CT2 heater burnout detected.
3 SSR open circuit ssro SSR
indicator lit SSR open circuit detected (when
heater current
cannot be
detected with
temperature
control gate output
ON).
4 SSR short circuit ssrs SSR
indicator lit SSR short circuit detected (when
heater current is
detected with
temperature
control gate output
OFF).
5 Heater layer short
1
hrs1 ALM
indicator lit CT1 overcurrent detected.
6 Heater layer short
2
hrs2 ALM
indicator lit CT2 overcurrent detected.
Processing
value name
Display
characters
Display
range
Unit Function
Heater 1
current
ct 1 0100 to 2300
(See notes 1
and 2.)
A This is the CT1 heater
current processing value.
Alarm operations such as
the heater burnout alarm
are determined based on
this processing value.
Heater 2
current
ct 2 0100 to 2300
(See notes 1
and 2.)
A This is the CT2 heater
current processing value.
Alarm operations such as
the heater burnout alarm
are determined based on
this processing value.

K8AC-H
15
■Settings Method
Settings Methods for SSR and Contactor Control Heaters
Setting Conditions
Detecting burnouts in just one heater when ten 300-W rated heaters
are connected in parallel to a single-phase 200-V power supply.
The heater is SSR controlled.
Normal Heater Current and Heater Current
with One Heater Element Burnout
Normal current = (300 W ×10 (heaters))/200 V = 15.0 A
Current with one burnout = (300 W ×9)/200 V = 13.5 A
Heater burnout alarm set value =
Selecting Heater Element Burnout Detector
Models
For the above example, K8AC-H12C@-FLK would be selected.
The burnout alarm set value is 14.3 A, so the current range 2.00 to
22.00 A should be selected.
SSR control is used, so type C should be selected. (Type C is also
selected for contactor control.)
Select the appropriate relay or transistor output specifications,
depending on the application.
K8AC-H Parameter Setting Procedure
(Only the minimum settings are shown here. Refer to pages 18 to 21
for information on how to set parameters.)
1. Turn ON the power to the K8AC-H. The initial status when power
is turned ON is called RUN mode.
2. Press the LKey for at least 3 s to change from RUN mode to
ADJ mode (the mode for adjusting burnout alarm set values.)
3. Set the burnout alarm set values. (AL-1 = CT1 burnout alarm set
value and AL-2 = CT2 burnout alarm set value.)
Set “14.3” to AL-1.
Set the AL-2 burnout alarm set value to “----” so that it will not
detect heater burnout, because this is a single-phase heater.
4. Change to RUN mode.
Press the L Key while in ADJ mode for at least 1 s to change to
RUN mode.
5. Check operation.
Test heater burnout detection by burning out one heater.
Also check that there are no malfunctions during temperature
control.
Note: The default setting for functions including the voltage
fluctuation compensation function, hysteresis, output ON delay
time, and SSR error detection function is OFF. Turn ON any of
these functions as required.
Settings Method for Cyclic and Phase Control Heaters
Settings Conditions
Detecting burnouts in one heater when five 1,000 W-rated heaters
are connected to each phase of a three-phase delta-connected 200-
V power supply.
A power regulator (phase control) performs heater control.
Normal Heater Current and Heater Current
With One Heater Element Burnout
Normal current = ×(1,000 W ×5 (heaters))/200 V = 43.3 A
Current with one burnout = ×(1,000 W ×4)/200 V = 39.1 A
Heater burnout alarm set value =
Selecting Heater Element Burnout Detector
Models
For the above example, K8AC-H13P@-FLK would be selected.
The burnout alarm set value is 41.2 A, so the current range 20.0 to
200.0 A should be selected.
Phase control is used, so type P should be selected. (Type P is also
selected for cyclic control.)
Select the appropriate relay or transistor output specifications,
depending on the application.
K8AC-H Parameter Settings Procedure
(Only the minimum settings are shown here. Refer to pages 18 to 21
for information on how to set parameters.)
1. Turn ON the power to the K8AC-H. The initial status when power
is turned ON is called RUN mode.
2. Press the LKey for at least 3 s to change from RUN mode to
ADJ mode (the mode for adjusting burnout alarm set values.)
3. Change from ADJ mode to SET mode (the default settings mode
for all functions). The password “0169” is required to move to SET
mode.
4. Set the heater control method parameter to PH-3 (three-phase
control).
The default setting is PH-1 (single-phase control).
Note: Set the parameter to CYCL (cyclic control) when using
cyclic control.
5. Press the L Key for at least 1 s to change from SET mode to
ADJ mode. Press the LKey again for at least 1 s to change from
ADJ mode to RUN mode.
Note: The default setting for functions including the voltage
fluctuation compensation function, hysteresis, output ON delay
time, and SSR error detection function is OFF. Turn ON any of
these functions as required.
(Normal current + current at malfunction) =15.0+13.5 = 14.3 A
22
Normal current + current at malfunction =43.3+39.1 =41.2A
22
3
3

K8AC-H
16
Burnout Alarm Set Value Setting Method
Setting Method
•Wire the K8AC-H, temperature controller (4 to 20 mA current output
type), and power regulator (phase control).
•Press the LKey on the K8AC-H for at least 3 s to change from
RUN mode to ADJ mode.
•AL-1 (CT1 burnout alarm set value) will be displayed when the
mode is changed to ADJ mode. Press the Skey once when AL-1
is displayed. Next, press the UKey once. The present heater
current value will be displayed on the main display, so note this as
the normal current value. Always have the temperature controller
output at 20.0 mA at this time. (See note 1.)
•Next, disconnect one heater and note the heater current in this
burnout state. Alternatively, use the current when one heater is
burned out (calculated earlier) as the current during malfunction. It
is recommended that the current at an actual burnout is confirmed.
•Set the K8AC-H burnout alarm set value based on the results. The
burnout alarm set value is set at the mid-point between the normal
current and the current at malfunction, taking errors and variations
in heater capacity into consideration.
•In this setting example, the set value for AL-2 (CT2 burnout alarm
setting) is the same as the set value for AL-1. (See note 2.)
Note: 1. The K8AC-H automatically adjusts burnout alarm setting
levels to compensate based on the temperature controller
current output. The burnout alarm set value must be set
when the temperature controller output is at 100% (20 mA),
so be sure to have the temperature controller at 20 mA
output.
2. If the heater capacity is unbalanced, the CT1 and CT2
burnout alarm levels may not be at the same value.
■Measurement Monitor Value Display Ranges and Functions
Other than measuring the heater current, the K8AC-H can measure the power supply voltage, maximum/minimum current, maximum/minimum
voltage, and other values. The measurement data can be monitored from a host using RS-485 communications. The measurement monitor value
names, display ranges, and functions are given in the following table.
Note: Each measurement monitor value can be individually reset. Refer to the K8AC-H Digital Heater Element Burnout Detector User’s Manual
(Cat. No. N132) for operating procedures.
Measurement monitor
value name
Display
characters
Display range Unit Function
Power supply voltage sce 0085 to 0264 V This is the K8AC-H control power supply voltage. When the voltage fluctuation
compensation function is enabled, the heater burnout determination based on this
voltage is automatically compensated.
Heater 1 maximum
current (See note.)
max1 0100 to 2300 A These hold the maximum and minimum values for each processing value.
•The maximum and minimum heater currents after the power is turned ON or
after a maximum or minimum reset are displayed.
•The values are not saved when power is interrupted.
•The current values are not refreshed when startup lock is in effect and when the
gate input is enabled but the gate input is OFF.
•Power supply voltages are always refreshed.
Heater 1 minimum current
(See note.)
min1 0100 to 2300 A
Heater 2 maximum
current (See note.)
max2 0100 to 2300 A
Heater 2 minimum current
(See note.)
min2 0100 to 2300 A
Maximum power supply
voltage (See note.)
maxs 0085 to 0264 V
Minimum power supply
voltage (See note.)
mins 0085 to 0264 V
Number of alarm outputs acnt 0000 to 9999 Outputs This value counts the total number of alarms output for heater burnout, SSR open
and short circuits, and heater overcurrent.
•The count is refreshed each time an alarm is output, and it is saved in non-
volatile memory.
•The value is saved when power is interrupted.
•The number of outputs is not counted for the test function.
Processing value for
alarm output
memo 0100 to 2300 A This holds the CT1 or CT2 processing value when a heater burnout alarm is output.
•This is the most recent processing value, and it is refreshed each time a heater
burnout alarm occurs.
•The value is not saved when power is interrupted.
Run time otim 0000 to 9999 × 10h This is the total run time value from when power is turned ON or the processing
value is reset until an alarm occurs.
•The total time is recorded in non-volatile memory approximately once per hour. If
power is interrupted within the hour, however, the data since the beginning of the
hour is lost and the total starts over from when the time was last saved.
•The total is stopped during heater burnout alarm output. When the alarm is
cleared, the total resumes from the time just before the alarm occurred.
Heater 1 input shift display
current
isc1 −999 to 999 A This is the shift value for displaying the CT1 heater current measurement set in
measurement parameter CT1.
•The value is saved when power is interrupted.
Heater 2 input shift display
current
isc2 −999 to 999 A This is the shift value for displaying the CT2 heater current measurement set in
measurement parameter CT2.
•The value is saved when power is interrupted.

K8AC-H
17
■Modes
Groups of setting items are called “modes.” The K8AC-H has five modes.
Note: If more than five minutes elapses with no operations performed in the Protection Settings mode, ADJ mode, or SET mode, the status will
return automatically to the processing value display. If this occurs while settings are in progress, it may cause unintended operations in the
processing value display. Be careful not to allow this to happen.
■Settings Data Notation
The letters of the alphabet in settings data are displayed as shown below.
Mode Function Alarm operation
RUN This is the normal operating mode, used for receiving inputs, executing heater burnout outputs, etc.
Operation goes into RUN mode immediately after power is turned ON. Executed
ADJ This mode is used to change comparatively frequently set parameters, such as alarm value settings.
This also the mode for entering the password to move to the SET mode. Stopped
SET This mode is used to make the initial settings for the various functions. Stopped
Protection Settings This mode is used to make settings to prevent unintended key operations. The protected modes are not
displayed, preventing changes to set values. Stopped
TEST This mode is used to simulate inputs with key operations to test alarm outputs. Executed
GATE This mode sets the gate current value that stops an alarm or detection. Executed
ABCDEFGH I JKLMNOPQRSTUVWXYZ
abcdefghijklmnopqrstuVwxyz

K8AC-H
18
Operating Procedures
■Moving between Modes
To ADJ Mode
When the Lkey is pressed for one second in RUN mode, the 7-
segment display will begin to flash. If the key is held down for another
two seconds, the mode will be switched to ADJ mode.
To return to RUN mode from ADJ mode, press the Lkey for at least
one second.
To Protection Settings Mode
When the Land Mkeys are pressed for one second n RUN mode,
the 7-segment display will begin to flash. If the keys are held down
for another five seconds, the mode will be switched to Protection
Settings mode. To return to RUN mode from Protection Settings
mode, press Land Mkeys for at least one second.
To GATE Mode
When the Dkey is pressed for at least one second in RUN mode,
the mode will be switched to GATE mode. To return to RUN mode
from GATE mode, press the Dkey for at least one second.
To TEST Mode
When the Skey is pressed for at least one second in RUN mode,
the mode will be switched to TEST mode. To return to RUN mode
from TEST mode, press the Skey for at least one second.
To SET Mode (Password Input)
A special operation is required to move to the SET mode.
Use the following procedure.
■Setting the Parameter
The value set for each parameter is called the “set value.” Set values
include both numbers and characters.
The status when a set value is displayed is called “monitor status,”
and when it can be changed it is called “change status.”
Use the following procedure to display and change set values.
Procedure
1234
1234
Hold down for at
least another 2 s.
Password: 0169
When the key
is released
Power ON
RUN mode TEST mode
ADJ mode
SET mode
Protection
settings mode Press the
Land M
keys for at
least 1 s.
Press the L
and Mkeys for
5 s.
Press the
Lkey for
at least 1s.
Press the Lkey
for at least 1 s.
Press the S
key for at least 1 s.
Press the Lkey
for at least 1s.
When the
key is
released
Press the S
key for at least 1 s.
Press the
Land M
keys.
Press the D
key for at least 1 s.
Press the D
key for at least 1 s. GATE mode
init
SET mode
Next parameter
in ADJ mode
00000
0000
0169
0
amoV
amoV
M
MMM
SS 0169
S
When password
is incorrect
When password
is correct
Move to the ADJ mode and use the Mkey to display
the parameter for moving to the SET mode.
·The parameter characters are "amoV".
A.
Press the Skey to display the set value
(password).
B.
Press the Skey again to enable changing
the password.
C.
Use U, D, and Skeys to set the password.
The password is 0169.
·Press the Mkey.
·If the password is correct, the mode will change to
the SET mode.
·If the password is incorrect, the next parameter will
be displayed while still in ADJ mode.
D.
Procedure
Monitor status Change status
To next parameter
Use the S, U, and
Dkeys to change
the set value.
2000 2000al-1
M
MM
M
SS
Press the Skey while a parameter is displayed to
go into monitor status. The set value for that
parameter will be displayed.
A.
If the set value is not to be changed, press the M
key while in monitor status to switch to the next
parameter.
B.
Press the Skey again while in monitor status to
enable the changing set value.
·The place where the set value can be changed will
begin to flash.
C.
Press the Mkey to save the changed set value in
internal memory and switch to the next parameter.
·Changed set values will not be saved in memory if
the mode is changed by another key operation
without first pressing the Mkey.
E.
Use the S, U, and Dkeys to change the set
value.
D.
Note:
If a set value is out of
range, either too high or too
low, the maximum or
minimum value will
automatically be set. For
models with a current input
of 0.200 to 2.200 A, for
example, the maximum
value is 2.200 and the
minimum value is 0.200.

K8AC-H
19
■Parameter List
The setting items in each mode are called “parameters.” Parameters can be switched by using the Mkey.
Note: 1. Displayed when the Selectable Protection Level parameter is set to 0.
2. Displayed by the K8AC-H@@P@-FLK.
3. If more than five minutes elapses with no operations performed in Protection Settings mode, ADJ mode, SET mode, or for a measurement
parameter, the status will return automatically to the processing value display. If this occurs while settings are in progress, it may cause
unintended operations to be performed in the processing value display. Be careful not to allow this to happen.
4. Displayed by the K8AC-H@@C@-FLK.
Heater 1 current
Heater 2 current
Power supply
voltage
Heater 1
maximum current
Heater 1
minimum current
Heater 2
maximum current
Heater 2
minimum current
Maximum power
supply voltage
(Processing value
display status)
Heater 2 input shift
display current
Heater 1 input shift
display current
Minimum power
supply voltage
Number of
alarm outputs
Processing value
for alarm output
RUN time
See note 1.
Voltage
fluctuation
compensation
standard value
Password for
moving to SET
mode: 0169
Burnout alarm
value 1
Heater layer short
alarm set value
Heater layer short
detection
SSR open circuit
detection
SSR short circuit
detection
Output ON delay
Soft startup time
Startup lock time
Voltage fluctuation
compensation
Gate input function
Alarm hysteresis 2
Alarm hysteresis 1
Processing value
initialization
All initialization
Set value initialization
Heater control
method
Switchable
display
Power save
mode
Power save
mode standby
time
Display mode
Display
refresh time
Unit number
Baud rate
Data length
Stop bits
Parity bit
Gate OFF
output hold time
See note 3.
Protection Settings mode
ADJ Mode
RUN mode
Measurement
parameters
SET mode
Selectable protection level
Setting value change prohibition
1 s min.
1 s min.
1 s min.
3 s min.
See note 3.
See note 3.
Power ON
5 s min.
Burnout alarm
value 2
See note 3.
See note 2.
init
sini
pini
hys1
hys2
gate
comp
stim
odly
soft
ssht
sopn
hrst
hral
msmd
dsel
psmd
pstm
dsmd
dsrf
u no
bps
len
sbit
prty
goht
al-1
al-2
ct 1
ct 2
sce
max1
min1
max2
min2
maxs
isc2
isc1
otim
memo
acnt
min5
1234
VfcV
amoV
aspt
wtpt
1 s min.
1 s min.
1 s min.
TEST mode
test
GATE mode
g-lV
1 s min.
An alarm is output if
the test value falls
below the burnout
alarm value 1 setting.
Alarm or detection is
stopped if the gate
current value falls
below the set value.
See note 2.
See note 4.

K8AC-H
20
■Parameter Defaults and Descriptions
Note: Shaded parameters must always be set regardless of the measurement method.
Item
Mode
Parameter name Description Parameter Setting range Default
Protection
Settings
Selectable Protection Level Restrict access to Adjust Mode (ADJ) and or
Setting Mode (SET) from RUN mode.
0: Access enabled to both ADJ and SET.
1: Access enabled to ADJ and disabled to SET.
2: Access disabled to both ADJ and SET.
aspt 0 to 2 0
Setting Value Change Prohibition Prohibits changes to set values. wtpt ON/OFF OFF
ADJ Burnout Alarm
Value 1
K8AC-H@1 Sets the output operation value for the burnout
alarm.
Note: The burnout alarm function can be
disabled by setting the set value to “−”.
al-1 0.200 to 2.200 A 1.000 A
K8AC-H@2 2.00 to 22.00 A 10.00 A
K8AC-H@3 20.0 to 200.0 A 100.0 A
Burnout Alarm
Value 2
K8AC-H@1 Sets the output operation value for the burnout
alarm.
Note: The burnout alarm function can be
disabled by setting the set value to “−”.
al-2 0.200 to 2.200 A 1.000 A
K8AC-H@2 2.00 to 22.00 A 10.00A
K8AC-H@3 20.0 to 200.0 A 100.0 A
Voltage Fluctuation Compensation
Standard Value
Sets the standard voltage used by the voltage
fluctuation compensation function. The
fluctuation compensation function operates in
respect to this set value.
vfcv 100 to 240 VAC 100 V
SET All Initialization Returns all set values and measurement values
to their default settings.
init ON/OFF OFF
Set Value Initialization Returns all set values to their default settings. sini ON/OFF OFF
Processing Value Initialization Returns all measurement values to their default
settings.
pini ON/OFF OFF
Alarm Hysteresis 1 Sets hysteresis for the alarm output value for
burnout detection (undercurrent) and heater
layer shorts (overcurrent) for CT1.
hys1 1 to 999 10
Alarm Hysteresis 2 Sets hysteresis for the alarm output value for
burnout detection (undercurrent) and heater
layer shorts (overcurrent) for CT2.
hys2 1 to 999 10
Gate Input Function Turns the gate input function ON and OFF. If the
gate input is turned OFF, application as a simple
ammeter is possible.
gate ON/OFF ON
Voltage Fluctuation Compensation Turns the voltage fluctuation compensation
function ON and OFF.
comp ON/OFF OFF
Startup Lock Time Sets the lock time for the startup lock. stim 0 (OFF) to 255 s 0 (OFF)
Output ON Delay Sets the output delay time. Set this parameter to
set the operating time.
odly 0.0 (OFF) to 99.9 s 0.0
(OFF)
Soft Startup Time Sets the soft startup time. Set this parameter only
when using a soft start function with the power
regulator.
soft 0.0 (OFF) to 99.9 s 0.0
(OFF)
SSR Short Circuit Detection Turns the SSR short circuit detection function ON
and OFF.
ssht ON/OFF OFF
SSR Open Circuit Detection Turns the SSR open circuit detection function ON
and OFF.
sopn ON/OFF OFF
Heater Layer Short Detection
(Overcurrent Detection)
Turns the heater layer short (overcurrent)
detection function ON and OFF.
hrst ON/OFF OFF
Heater Layer Short
Alarm Level
(Overcurrent
Alarm Set Value)
K8AC-H@1 Sets the operating level for heater layer short
(overcurrent) alarms.
Note: The heater layer short alarm level is the
same for both CT1 and CT2.
hral 0.200 to 2.200 A 2.000 A
K8AC-H@2 2.00 to 22.00 A 20.00 A
K8AC-H@3 20.0 to 200.0 A 200.0 A
Heater Control Method
(See note 1.)
Sets the control method of the cyclic/phase
control heater.
msmd PH1, PH3, CYCL PH1
Switchable Display Sets the CT for which to normally display the
current.
dsel CT1, CT2 CT1
Power Save Mode Turns entering the power save mode ON and
OFF.
psmd ON/OFF OFF