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Three-phase Asymmetry and Phase-sequence Phase-loss Relay


Ideal for 3-phase Voltage Asymmetry Monitoring for Industrial Facilities and Equipment. 22.5 mm (W). One SPDT output relays


Rated input voltage K8AK-PA1 Three-phase, three-wire Mode: 200, 220, 230 and 240 VAC
Three-phase, four-wire Mode: 115, 127, 133 and 138 VAC
K8AK-PA2 Three-phase, three-wire Mode: 380, 400, 415 and 480 VAC
Three-phase, four-wire Mode: 220, 230, 240 and 277 VAC
Input load K8AK-PA1: Approx. 4.4 VA
K8AK-PA2: Approx. 4.4 VA
Operating value setting range (ASY.) Asymmetry set value: 2% to 22%
Operating value Asymmetry operating value = Rated input voltage × Asymmetry set value (%)
The asymmetry operation will function when the potential difference between the highest and lowest voltage phases equals or exceeds the asymmetry operating value.
Reset value setting range (HYS.) 5% of operating value (fixed)
Reset method Automatic reset
Operating time
setting range (T)
Asymmetry 0.1 to 30 s
Phase sequence 0.1 s±0.05 s
Phase loss 0.1 s max.
Power ON lock time (LOCK) 1 s/5 s (Changed with the DIP switch.)
Indicators Power (PWR): Green, Relay output (RY): Yellow, Alarm outputs (ALM): Red
Output relays One SPDT relay (NC operation)
Output relay ratings 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/30 VDC: 100,000 operations
Ambient operating temperature -20 to 60°C (with no condensation or icing)
Storage temperature -25 to 65°C (with no condensation or icing)
Ambient operating humidity 25% to 85% (with no condensation)
Storage humidity 25% to 85% (with no condensation)
Altitude 2,000 m max.
Terminal screw tightening torque 0.49 to 0.59 N·m
Terminal wiring method Recommended wire
 Solid wire: 2.5 mm2
 Twisted wires: AWG16, AWG18
 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
Case color N1.5
Case material PC and ABS, UL 94 V-0
Weight Approx. 130 g
Mounting Mounts to DIN Track.
Dimensions 22.5 × 90 × 100 mm (W×H×D)


Input frequency 50/60 Hz
Overload capacity Continuous input at 115% of maximum input, 10 s at 125% (up to 600 VAC).
Operating value ±0.5% full scale (at 25°C and 65% humidity, rated power supply voltage, 50/60 Hz
sine wave input)
Operating time ±50 ms (at 25°C and 65% humidity, rated power supply voltage)
Conforming standards EN 60947-5-1
Installation environment (pollution level 2, installation category III)
EMC EN 60947-5-1
Safety standards UL 508 (Recognition), Korean Radio Waves Act (Act 10564),
CSA: C22.2 No.14, CCC: GB/T 14048.5
Insulation resistance 20 MΩ min.
Between external terminals and case
Between input terminals and output terminals
Dielectric strength 2,000 VAC for one minute
Between external terminals and case
Between input terminals and output terminals
Noise immunity 1,500 V power supply terminal common/normal mode
Square-wave noise of ±1 μs/100 ns pulse width with 1-ns rise time
Vibration resistance Frequency: 10 to 55 Hz, 0.35-mm single amplitude
10 sweeps of 5 min each in X,Y, and Z directions
Shock resistance 100 m/s2, 3 times each in 6 directions along 3 axes
Degree of protection Terminals: IP20

Relationship of Mounting Distance between K8AK-PA Relays and Ambient Temperature (Reference Values)

The following diagram shows the relationship between the mounting distances and the ambient temperature.
If the relay is used with an ambient temperature that exceeds these values, the temperature of the K8AK may rise and shorten the life of the internal components.

K8AK-PA Specifications 3