Omron K8DS-PH1 Phase Loss Relay

Omron K8DS-PH1 is a compact, DIN rail-mountable phase-sequence and phase-loss monitoring relay designed for three-phase systems operating between 200 and 480 VAC. It ensures proper phase sequence and detects phase loss, providing protection against reverse motor operation and potential equipment damage. 

Key Specifications

• Input Voltage: 3-phase, 200 to 480 VAC (3-wire)

• Output: SPDT relay, rated at 5 A at 250 VAC or 30 VDC

• Operating Time:

  • Phase sequence detection: 0.1 s ±0.05 s

  • Phase loss detection: 0.1 s max (when voltage drops rapidly from 100% to 0% of rated voltage)

• Reset Method: Automatic reset

• Indicators: Green LED for power (PWR), Yellow LED for relay output (RY)

• Mounting: DIN rail

• Dimensions: 17.5 mm width

• Operating Temperature: −20 to 60°C (with no condensation or icing)

• Storage Temperature: −25 to 65°C (with no condensation or icing)

• Humidity: 25% to 85% (with no condensation)

• Altitude: Up to 2,000 m

• Terminal Wiring:

  • Recommended wire: Solid wire up to 2.5 mm²; Twisted wires: AWG16, AWG18

  • Terminal screw tightening torque: 0.49 to 0.59 N·m

• Case Material: PC and ABS, UL 94 V-0 

Functional Highlights

• Phase Loss Detection: The K8DS-PH1 detects phase loss by monitoring voltage imbalance. Detection occurs when the imbalance is 80% of the maximum phase voltage. It’s important to note that phase loss detection may not be reliable under light motor load conditions due to insufficient voltage imbalance.

• Phase Sequence Monitoring: Ensures correct phase sequence to prevent reverse operation of motors.

• Automatic Reset: After detecting and signaling a fault, the relay automatically resets once normal conditions are restored.

• LED Indicators: Provide clear visual status of power supply and relay output, facilitating easy monitoring and diagnostics. 

Applications

The K8DS-PH1 is suitable for various industrial applications where monitoring of phase sequence and phase loss is critical, such as 

• Industrial machinery

• Motor control circuits

• HVAC systems

• Pumps and compressors

• Elevators and escalators