Single-phase Overvoltage/Undervoltage Relay
K8AK-VW
Ideal for Voltage Monitoring for
Industrial Facilities and Equipment.
• Monitor for overvoltages and undervoltages simultaneously.
Separate settings and outputs supported for overvoltages and
undervoltages.
• Manual resetting and automatically resetting supported by one
Relay.
• Pre-alarm Monitoring Mode.
• Two SPDT output relays, 5 A at 250 VAC (resistive load).
• Process control signal (0 to 10 V) and current splitter input
supported.
• Output status can be monitored using LED indicator.
• Input frequency of 40 to 500 Hz supported.
• Inputs are isolated from the power supply.
Refer to
Safety Precautions
on page 9.
Refer to page 8 for commonly asked questions.
For the most recent information on models that have been certified for
safety standards, refer to your OMRON website.
Ordering Information
List of Models
Setting range
1 to 10 V AC/DC
3 to 30 V AC/DC
15 to 150 V AC/DC
20 to 200 V AC/DC
30 to 300 V AC/DC
60 to 600 V AC/DC
Power supply voltage
24 VAC/DC
100 to 240 VAC
24 VAC/DC
100 to 240 VAC
Model
K8AK-VW2 24 VAC/DC
K8AK-VW2 100-240 VAC
K8AK-VW3 24 VAC/DC
K8AK-VW3 100-240 VAC
Ratings and Specifications
Input Range
Model
K8AK-VW2
Range*
0 to 10 V AC/DC
0 to 30 V AC/DC
0 to 150 V AC/DC
0 to 200 V AC/DC
K8AK-VW3
0 to 300 V AC/DC
0 to 600 V AC/DC
Connection terminal
V1-COM
V2-COM
V3-COM
V1-COM
V2-COM
V3-COM
Setting range
1 to 10 V AC/DC
3 to 30 V AC/DC
15 to 150 V AC/DC
20 to 200 V AC/DC
30 to 300 V AC/DC
60 to 600 V AC/DC
Input impedance
Approx. 120 kΩ
Approx. 320 kΩ
Approx. 1.6 MΩ
Approx. 1.2 MΩ
Approx. 1.7 MΩ
Approx. 3.1 MΩ
Continuous input at 115% of
maximum input.
Overload capacity
10 s at 125%
(up to 600 VAC)
* The range is selected using connected terminals.
1
K8AK-VW
Ratings
Power supply
voltage
Isolated power supply
24 VAC/DC
100 to 240 VAC
24 VAC/DC: 2.0 VA/1.1 W max.
100 to 240 VAC: 4.6 VA max.
Power consumption
10% to 100% of the maximum value of the setting range
K8AK-VW2: 1 to 10 V AC/DC
3 to 30 V AC/DC
Operating value setting range (AL1 and AL2)
15 to 150 V AC/DC
K8AK-VW3: 20 to 200 V AC/DC
30 to 300 V AC/DC
60 to 600 V AC/DC
Operating value
Reset value
Reset method
Operating time setting range (T)
Power ON lock time (LOCK)
Indicators
Input impedance
Output relays
100% operation at set value
5% of operating value (fixed)
Manual reset/automatic reset (switchable)
Note:
Manual reset: Turn OFF power supply for 1 s or longer.
0.1 to 30 s
1 s or 5 s (Switched using DIP switch.)
Power (PWR): Green, Relay output (RY): Yellow, Alarm outputs (AL1, AL2): Red
Refer to
Input Range
on previous page.
Two SPDT relays (NC operation)
Rated load
Resistive load
5 A at 250 VAC
5 A at 30 VDC
Maximum switching capacity: 1,250 VA, 150 W
Minimum load: 5 VDC, 10 mA (reference values)
Mechanical life: 10 million operations min.
Electrical life: 5 A at 250 VAC or 30 VDC: 50,000 operations
3 A at 250 VAC or 30 VDC: 100,000 operations
−20
to 60°C (with no condensation or icing)
−25
to 65°C (with no condensation or icing)
25% to 85% (with no condensation)
25% to 85% (with no condensation)
2,000 m max.
0.49 to 0.59 N·m
Recommended wire
Solid wire: 2.5 mm
2
Twisted wires: AWG16, AWG18
Note: 1.
Ferrules with insulating sleeves must be used with twisted wires.
2.
Two wires can be twisted together.
Recommended ferrules
Al 1,5-8BK (for AWG16) manufactured by Phoenix Contact
Al 1-8RD (for AWG18) manufactured by Phoenix Contact
Al 0,75-8GY (for AWG18) manufactured by Phoenix Contact
N1.5
PC and ABS, UL 94 V-0
Approx. 150 g
Mounts to DIN Track.
22.5
×
90
×
100 mm
(W×H×D)
Output relay ratings
Ambient operating temperature
Storage temperature
Ambient operating humidity
Storage humidity
Altitude
Terminal screw tightening torque
Terminal wiring method
Case color
Case material
Weight
Mounting
Dimensions
2
K8AK-VW
Specifications
Allowable operating voltage range
Allowable operating frequency range
Input frequency range
Overload capacity
Repeat error
Operating value
Operating time
Conforming standards
Applicable stan-
dards
EMC
Safety standards
85% to 110% of rated power supply voltage
50/60 Hz
±5
Hz
40 to 500 Hz
Continuous input at 115% of maximum input, 10 s at 125% (up to 600 VAC).
±0.5%
full scale (at 25°C and an ambient humidity of 65% at the rated power supply voltage, DC and 50/60
Hz sine wave input)
±50
ms (at 25°C and 65% humidity, rated power supply voltage)
EN 60947-5-1
Installation environment (pollution level 2, installation category III)
EN 60947-5-1
UL 508 (Recognition), Korean Radio Waves Act (Act 10564),
CSA: C22.2 No.14, CCC: GB/T 14048.5
20 MΩ min.
Between all external terminals and the case
Between all power supply terminals and all input terminals
Between all power supply terminals and all output terminals
Between all input terminals and all output terminals
2,000 VAC for 1 min
Between all external terminals and the case
Between all power supply terminals and all input terminals
Between all power supply terminals and all output terminals
Between all input terminals and all output terminals
1,500 V power supply terminal common/normal mode
Square-wave noise of ±1
μs/100
ns pulse width with 1-ns rise time
Frequency: 10 to 55 Hz, 0.35-mm single amplitude
10 sweeps of 5 min each in X,Y, and Z directions
100 m/s
2
, 3 times each in 6 directions along 3 axes
Terminals: IP20
Insulation resistance
Dielectric strength
Noise immunity
Vibration resistance
Shock resistance
Degree of protection
Connections
Terminal Diagram
K8AK-VW2 100-240VAC
A
Control Output
Relay output
250 VAC, 5 A (resistive load)
30 VDC, 5 A (resistive load)
B
Relay Output
Common
21
24
AL2
22
V1
V2
V3
21
24
22
A
Voltage Input
VW2
VW3
V1
V2
V3
V1
V2
V3
150 V max.
30 V max.
10 V max.
300 V max.
200 V max.
600 V max.
C
C
B
Power Supply Voltage
100 to 240 VAC
A1
A2
24 VAC/DC
A1
A2
A1
A2
C
Relay Output
Common
AL1
11
12
14
(No polarity)
11
12
14
Note: 1.
2.
3.
4.
There is no polarity for the DC power supply input.
For the voltage input, you can input only from the C terminal and one other terminal.
Refer to
Setting Ranges and Wiring Connections
for information on the V1, V2, and V3 voltage input terminals.
Use the recommended ferrules if you use twisted wires.
3
K8AK-VW
Wiring Example
Single-phase
power supply
Load
21
V1
24
V2
22
V3
Power supply
AC/DC
A2
Power
supply
voltage
A1
A1
11
A2
12
C
14
Timing Charts
●Overvoltage
and Undervoltage Operation
Diagram
DIP switch settings: SW3 and SW4 both ON or both OFF.
Power supply
voltage
Overvoltage set
value
(AL1)
Hysteresis: Fixed at 5%
●Undervoltage
and Undervoltage Operation
Diagram (Undervoltage Pre-alarm Mode)
DIP switch settings: SW3 OFF and SW4 ON.
Power supply
voltage
Input
Undervoltage set
value
(AL1)
Hysteresis: Fixed at 5%
Undervoltage set
value
(AL2)
Hysteresis: Fixed at 5%
Input
Undervoltage set
value
(AL2)
Flashing
AL1 alarm indicator
Flashing
AL2 alarm indicator
Overvoltage (AL1) relay
(11-14)
Undervoltage (AL2) relay
(21-24)
Delay: 250 ms
(reference
value)
Lit
Lit
Hysteresis: Fixed at 5%
Flashing
AL1 alarm indicator
Flashing
AL2 alarm indicator
Undervoltage (AL1) relay
(11-14)
Undervoltage (AL2) relay
(21-24)
Lit
Lit
t
t: Operating time (0.1 to 30 s)
Delay: 250 ms
(reference
value)
t1: Power ON lock (1 s or 5 s)
t1
Delay: 250 ms
(reference
value)
Delay: 250 ms
(reference
value)
t
t1
t: Operating time (0.1 to 30 s)
t1: Power ON lock (1 s or 5 s)
Note: 1.
The K8AK-VW@ output relay is normally operative.
2.
The power ON lock prevents unnecessary alarms from
being generated during the instable period when the power
is first turned on. There is no relay output during timer
operation.
Note: 1.
The K8AK-VW@ output relay is normally operative.
2.
The power ON lock prevents unnecessary alarms from
being generated during the instable period when the power
is first turned on. There is no relay output during timer
operation.
●Overvoltage
and Overvoltage Operation
Diagram (Overvoltage Pre-alarm Mode)
DIP switch settings: SW3 ON and SW4 OFF.
Power supply
voltage
Overvoltage setting (AL1)
Hysteresis: Fixed at 5%
Overvoltage setting (AL2)
Hysteresis: Fixed at 5%
Input
Flashing
AL1 alarm indicator
AL2 alarm indicator
Overvoltage (AL1) relay
(11-14)
Overvoltage (AL2) relay
(21-24)
Flashing
Lit
Lit
t1: Power ON lock (1 s or 5 s)
t1
Delay: 250 ms
(reference
value)
Delay: 250 ms
(reference
value)
Note: 1.
The K8AK-VW@ output relay is normally operative.
2.
The power ON lock prevents unnecessary alarms from
being generated during the instable period when the power
is first turned on. There is no relay output during timer
operation.
4
K8AK-VW
Nomenclature
Front
Terminal
block
(See notes 1 and 2.)
●Indicators
Item
Power indicator
(PWR: Green)
Relay status indicator
(RY: Yellow)
Voltage knob (AL1)
Meaning
Lit when power is being supplied.
Lit when relay operates (Not light when
both AL1 and AL2 are in error status) (Nor-
mally lit)
Lit when there is an overvoltage or under-
voltage.
The indicator flashes to indicate the error
status after the input has exceeded the set
value while the operating time is being
clocked.
Power indicator
Voltage knob (AL2)
Relay status indicator
Alarm indicators
(AL1 and AL2: Red)
Alarm indicator
Operating time knob (T)
●Setting
Knobs
Item
Voltage
knob (AL1)
Voltage
knob (AL2)
Usage
Used to set the voltage to 10% to 100% of
maximum setting range.
Used to set the voltage to 10% to 100% of
maximum setting range.
Used to set the operating time to 0.1 to 30
s.
Terminal
block
(See notes 1 and 2.)
Operating time knob (T)
Note: 1.
Use either a solid wire of 2.5 mm
2
maximum or a ferrule with
insulating sleeve for the terminal connection.
The length of the exposed current-carrying part inserted into
the terminal must be 8 mm or less to maintain dielectric
strength after connection.
For 2.5 mm
2
or
smaller solid
wires
For ferrules
with
an insulation sleeve.
8
mm max.
8
mm max.
Recommended ferrules
Phoenix Contact
•
Al 1,5-8BK (for AWG16)
•
Al 1-8RD (for AWG18)
•
Al 0,75-8GY (for AWG18)
2.
Screw tightening torque: 0.49 to 0.59 N·m
3.
The terminal screw is a Pozidriv screw.
5
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