A-B Allen-Bradley

Functions and Applications

Product Overview

The 1402-LS51 Line Synchronization Module (LSM) belongs to Bulletin 1402 series. It is a 2-slot module with 1771 form factor, compatible with Allen‑Bradley PLC‑5 control systems and installed in standard 1771 I/O chassis. This legacy power control module has been discontinued by the original manufacturer and is mainly supplied as spare replacement parts for generator and cogeneration projects.

Key Functions

1. Automatic Synchronization of Dual Three-phase Power Systems It continuously measures voltage, frequency and phase difference between the generator bus to be paralleled and the reference utility grid. It outputs regulation signals to drive engine governors to achieve precise matching of voltage, frequency and phase, enabling safe generator paralleling and preventing severe inrush currents upon closure.
2. Load Sharing Control for Generators It acquires active power output of each generator, compares against total system load, and transmits deviation signals to realize automatic load distribution among multiple parallel generators, avoiding single-unit overload and unbalanced load distribution.
3. High-speed Multi-function Power Monitoring Measures comprehensive electrical parameters including three-phase voltage, current, frequency, power factor, active/reactive power, phase rotation and voltage unbalance ratio. Measurement data is transmitted to PLC‑5 via backplane for status monitoring and fault diagnosis.
4. Synchronization Status & Interlock Signal Output Provides discrete status signals such as synchronization ready, sync deviation and fault alarms. Coordinates with PLC logic to implement safety interlocks including paralleling enable and abnormal blocking.
5. Standard Backplane Data Communication Exchanges synchronization parameters, control commands and alarm data with PLC‑5 over the 1771 chassis backplane for centralized logic processing.

Typical Applications

Primarily deployed in diesel generator sets, gas generators, combined heat and power (CHP) plants and marine power stations. It controls paralleling between generators and utility mains as well as parallel operation of multiple generator units. Widely matched with legacy PLC‑5 power control systems. Currently it serves as maintenance spare parts for aging power stations and power equipment.

Note: Only compatible with 1771 chassis and PLC‑5 controllers; cannot be directly used on ControlLogix platforms.

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