A-B Line Synchronization Module (Bulletin 1402 LSM)

Chapter Objectives

After reading this chapter, you should be able to identify the product features and system applications.

Introduction

The Bulletin 1402, Line Synchronization Module (LSM), is designed to meet the needs of manufacturers, 

system integrators, and users of 3 phase alternators and cogeneration systems or for applications that require 

two three–phase systems to be synchronized with each other. 

The module provides means for automatic synchronization, load sharing, and high speed power system monitoring.

General Description

The Line Synchronization Module (LSM) is a two slot 1771 form factor module that fits into a standard Allen–Bradley 1771 I/O chassis. 

It performs three functions:

1. Measures appropriate parameters from the two three–phase systems and provides control and 

error signals to implement engine governor control for synchronization.

2. Provides an analog output that is representative of the ratio of the power being supplied by the alternator to the output rating of the alternator, 

reads an analog input that represents the ratio of the total system load being supplied to the total system capacity, 

and provides an error signal to adjust the alternator for proper load sharing based on the instantaneous load requirements.

3. Performs as a multi–function digital power monitor for the system.

These functions provide data and control signals which are communicated to the PLC-5 via the 1771 backplane.

Synchronization and Load Share Errors

In order to synchronize two three phase systems without high instantaneous

energy transfer, the voltage, frequency, and phase displacement of the two

systems must be matched. Kilowatt Load Sharing can be implemented by

matching the ratio of power system load to system capacity to the ratio of

actual alternator power to rated alternator power. The LSM provides the

following information to allow the user’s system to achieve the necessary control actions.

• Voltage Match Error (in steps of 0.05 percent)

• Frequency Match Error, or slip (in steps of 0.01 Hz)

• Synchronizing Bus to Reference Bus Phase Match Error (in steps of 1 degree)

• Load Sharing Error (scalar quantity between 0.000 and  1.000)

• Synchronization Status

— Frequency Within Limits

— Voltage Within Limits

— Phase Within Limits

— Synchronization Mode Conflict Failure

— Phase Rotation Mismatch Failure (3 phase synchronization mode only)

— No Reference Bus Voltage Present Failure

— No Synchronizing Bus Voltage Present Failure

— Reference Bus Over Voltage Failure

— Synchronizing Bus Over Voltage Failure

Measurements

In addition to the synchronization function, the LSM provides an extensive array of monitoring information 

for systems wired in Wye, Delta, or Open Delta. 

The monitored data is shown below: