Littelfuse 202 Monitor

3-PHASE VOLTAGE MONITOR/ 190-4

Littelfuse 202 Monitor – 3-Phase Voltage Monitor (190–480 VAC, Series 202)

The Littelfuse 202 3-Phase Voltage Monitor (Series 202) is a microcontroller-based protection relay engineered to safeguard motors and industrial equipment from harmful power line conditions. Designed for use with 190–480 VAC, 50/60 Hz systems, this compact voltage monitor continuously analyzes incoming voltage to detect overvoltage, undervoltage, phase loss, phase reversal, and voltage unbalance.

When an abnormal condition is detected, the internal SPDT output relay deactivates after a preset trip delay, helping prevent nuisance shutdowns caused by brief voltage fluctuations. Once voltage returns to acceptable levels, the relay automatically reactivates after the adjustable restart delay, ensuring safe and reliable system recovery.

This unit is ideal for protecting single-phase and three-phase motors, compressors, HVAC equipment, pumps, and industrial machinery.

Key Features & Benefits

• Wide Input Voltage Range: 190–480 VAC

• Compatible with 50/60 Hz (50 Hz increases delay timers by 20%)

• SPDT Output Relay for flexible control integration

• Microcontroller-based precision voltage sensing

• Adjustable Restart Delay: Manual; 2–300 seconds

• Trip Delay Protection:

  • Under/Over Voltage: 4 seconds

  • Unbalance/Phase Faults: 2 seconds

• Helps prevent nuisance tripping

• Compact Design: 2.5" H x 2.5" W x 1.4" D

• Operating Temperature: -40°F to 158°F (-40°C to 70°C)

• Humidity Rating: 95% non-condensing

Technical Specifications

• Input Voltage: 190–480 VAC

• Input Tolerance: ±10%

• Input Phase Sequence: A, B, C

• Overvoltage Trip: 110%

• Overvoltage Reset: 107%

• Undervoltage Trip: 90%

• Undervoltage Reset: 93%

• Voltage Unbalance Trip: 6%

• Voltage Unbalance Reset: 4.5%

• Repeat Accuracy: ±0.5%

• Trip Point Accuracy: ±1%

• Output Load Rating:

  • General Purpose: 10A @ 240 VAC

  • Pilot Duty: 480 VA @ 240 VAC

• Maximum Input Power: 5W

• Dielectric Breakdown: ≥1960

• Termination Type: 0.25" Male Quick Connect

• Mounting Method: 1/4" Socket Head Cap Screw (Customer Supplied)

• Dimensions: 2.5" H x 2.5" W x 1.4" D (63.5 x 63.5 x 35.6 mm)

Applications

• HVAC systems

• Industrial motor protection

• Pumps and compressors

• Refrigeration systems

• Manufacturing equipment

• Power distribution panels

Reliable Motor & Equipment Protection

Voltage disturbances such as imbalance, phase loss, overvoltage, and undervoltage can shorten motor life and cause costly downtime. The Littelfuse 202 3-Phase Voltage Monitor delivers accurate, fast-response protection with adjustable delays to maintain system stability and extend equipment lifespan.

Order today to ensure dependable voltage monitoring and long-term equipment protection.