Eaton T801V65N3D Motor Soft Starter Unit

Module Feature

T801V65N3D is Eaton Cutler-Hammer S801 series standard soft starter, V frame size, 650A rated operational current. The D suffix indicates inside-delta connection type, the soft starter is wired inside the motor delta winding, the actual starter current is only 0.577 times motor full load current, so it can drive higher power motor with same frame.

It adopts three-phase SCR voltage regulation and integrates built-in bypass contactor. After motor completes acceleration and reaches full speed, bypass contactor closes to bypass SCR and reduce power consumption and heat generation. N suffix means standard general firmware, no dedicated anti-water hammer pump deceleration curve. It supports comprehensive motor protection functions including overload, phase loss, phase unbalance, locked rotor and over-temperature. It can be equipped with external CIM communication module for Modbus RTU remote monitoring. Widely used for large fans, air compressors, belt conveyors and general heavy-duty motors.

Working principle

After receiving start command, the controller gradually increases SCR conduction angle, smoothly raises the voltage applied to motor winding to limit starting inrush current and realize soft acceleration.

When motor reaches rated speed, internal bypass contactor pulls in, SCR stops working. When stop command is triggered, voltage is gradually reduced to achieve soft stop. Protection circuit continuously monitors three-phase current and module temperature, it will cut off output and trigger alarm once abnormal condition occurs.

Onboard components

Three-phase SCR power stack, built-in bypass contactor, three current transformers, main control PCB, temperature sensor, cooling fan, main terminal lug assembly, operator panel interface.

LED indicators

Front panel LEDs indicate power, run status, bypass closed and fault alarm; matched operator panel can view current, thermal capacity and fault codes.

Hardware self‑diagnosis

Self-check covers input phase loss, three-phase current imbalance, SCR short circuit, module overtemperature, motor overload, locked rotor and parameter error. Fault timestamps and event logs are stored locally.

Programming software

Eaton configuration software for parameter backup, ramp time adjustment, Modbus address setup and firmware upgrade; local panel for on-site parameter modification and fault query.

Electrical & Process Parameters

Model:T801V65N3D Brand:Eaton (Cutler-Hammer) Series:S801 Device type:Inside Delta Three-phase Soft Starter Rated starter current:650 A Main circuit voltage:200~600V AC Control supply:24V DC Built-in bypass:Yes Communication:Optional Modbus RTU via CIM module Function:Soft start and soft stop for fan, compressor and general heavy-duty motors, inside delta wiring design

Mechanical & Structure

Mounting:Cabinet backplane mounting Frame:V frame Protection class:IP00 (open power type) Housing:Metal chassis

Environmental

Operating temperature:-30℃ ~ +50℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing Certification:CE, IEC60947-4-2, UL listed Status:Eaton original S801 soft starter spare

Installation

Install in ventilated MCC cabinet and reserve sufficient heat dissipation clearance. Wire according to inside delta wiring diagram, distinguish main power terminals and motor winding terminals.

Connect 24V control power, install CIM communication module if remote monitoring is required. Set start ramp, stop ramp, current limit and overload trip class. Perform start test and verify starting current. Keep cooling fan and air channel clean regularly.

Interface

L1/L2/L3 main input terminals, motor winding connection terminals, 24V control power terminals, CIM option interface, dry contact alarm relay terminals.

Diagnostic

Overcurrent trip: Mechanical jam, motor winding short circuit or improper current limit setting.

Phase loss fault: Input fuse blown, loose main cable terminal.

Over-temperature alarm: Fan failure, blocked air duct or frequent heavy-duty starting.

Bypass not closed: Bypass contactor coil fault or control circuit anomaly.

Product Brief

Eaton T801V65N3D S801 series inside-delta soft starter, 650A, 200–600V AC, built-in bypass contactor, general ramp algorithm, optional Modbus, suitable for fan, compressor and general heavy-duty motor soft start and stop.