Cut Sheet

© 2016 Littelfuse Protection Relays & Controls
Protection Relays
Motor and Pump Protection - 3-Phase Motor Protection
www.littelfuse.com/
Rev: 1-A-062816
www.littelfuse.com/777
777 SERIES
Description
The 777 is a fully programmable electronic overload relay
designed to protect any motor drawing 2-800 full load amps
(external CTs are required above 90 amps). The 777 (family
of products) is for 3-phase 200-480VAC applications, with
several specialized units for other voltage ranges and unique
applications. Common applications include conveyor systems,
HVAC equipment, saws and grinders, fan motors, and almost
any pumping application. Some unique applications include use
with a Subtrol
®
equipped Franklin submersible motor to detect
high motor temperatures and applications where a fast linear
trip is required.
All of the overload relays provide unsurpassed protection by
combining overload, voltage, phase loss and reversal, voltage
and current unbalance, power monitoring, and underload based
on current in one package. 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. The
units also feature a communications 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.
Features & Benefits
FEATURES BENEFITS
Built-in display
Visual indication for programming, viewing real-time
voltage or current, and last fault code
Programmable voltage
and current settings
Allows usage on wide range of systems
3 selectable
restart options
Choose from automatic, semi-automatic, or manual to
best meet individual application needs
3 programmable restart
delay timers
Program separate restart delay time for rapid cycle
protection, motor cool down, and dry-well recovery
Remote display
compatibility
Increases safety through remote display of real-time
data and fault history, without the need to open the
cabinet. Aids with arc flash safety regulations
Flexible reset
Reset can be done through pushbutton on relay or
remotely with optional 777-MRSW or OL-RESET
remote reset kit
Network
communications
capability
Compatible with Modbus, DeviceNet™, Profibus, or
Ethernet using optional communications module
3-Phase Current & Voltage Monitor
Wiring Diagram
TYPICAL WIRING DIAGRAM FOR MODEL 777
(20 TO 90 amps)
LITTELFUSE RECOMMENDS
USING CTs WITH TERMINALS TO
SIMPLIFY INSTALLATION.
12 - 16 AWG
STRANDED
WIRE
Ordering Information
See next page.
TYPICAL WIRING DIAGRAM FOR MODEL 777 (2 to 90 amps)
CURRENT TRANSFORMER WIRING DIAGRAM FOR MODEL 777
(80 to 800 amps)