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Series: 77C

Littelfuse 77C Current & Voltage Monitor Provides Exceptional Protection
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The single-phase 77C unit is a fully-programmable, electronic overload relay designed to protect any motor drawing 2-800 full load A (external CTs are required above 90 A). Common applications include conveyor systems, HVAC equipment, saws and grinders, fan motors, and almost any pumping application. The 77C and 777-HVR-SP (family of products) are for single-phase 100-240 V ac applications.

All of the overload relays provide unsurpassed protection by combining overload, underload, and voltage in one unit. For standalone applications, the units incorporate a 3-digit LED display that is used for programming, providing real-time operational information, and displaying diagnostic codes to aid in troubleshooting a fault condition. These units also feature a communications network port that can be used with communication modules, listed in the 777 accessories section, to form a Modbus, DeviceNet™, Profibus, or Ethernet network. Up to 99 units can be remotely monitored and controlled from a PC, PLC, or SCADA system, and data logging through a PC with the optional Solutions software. This capability allows for a simple, cost-effective way to meet new requirements for arc-flash safety.

  • Built-in display
  • Programmable voltage and current settings
  • 3 selectable restart options
  • 3 programmable restart delay timers
  • Remote display compatibility
  • Flexible reset
  • Network communications capability
  • Visual indication for programming, viewing real-time voltage or current, and last fault code
  • Allows usage on a wide range of systems
  • Choose from automatic, semi-automatic, or manual to best meet individual application needs
  • Program separate restart delay time for rapid cycle protection, motor cool down, and dry-well recovery
  • Increases safety through remote display of real-time data and fault history. Aids with arc-flash safety regulations
  • Reset can be done through pushbutton on relay or remotely with optional 777-MRSW or OL-Reset remote reset kit
  • Compatible with Modbus, DeviceNet™, Profibus, or Ethernet using optional communications module

77C Parts

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77C Applications

Highlights Section

  • Conveyor systems
  • HVAC equipment
  • Saws and grinders
  • Fan motors

Series: 77C Resources