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Chapter 3
CGCM-DLR Unit Operation
68
Synchronizing Control Software Interface
When synchronization is active, the CGCM-DLR unit adjusts the values of the
Scheduled Read table tags as described in the following section:
• Voltage Match Error as computed
• Frequency Match Error as computed
• Phase Match Error as computed
• Voltage Raise and Lower tags, which are set when the voltage match error
is above or below, respectively, the voltage acceptance window as defined
by the configured synchronizing voltage high and low limits
• Frequency Raise and Lower tags, which are set when the frequency match
error is above or below, respectively, the frequency acceptance window as
defined by the configured synchronizing frequency high and low limits
• Phase Raise and Lower tags, which are set when the phase match error is
above or below, respectively, the phase acceptance window as defined by
the configured synchronizing phase high and low limits
• The applicable Close Breaker tag, which is set when the voltage match
error, frequency match error and phase match error have all remained
continuously within their respective acceptance windows for the
configured acceptance window delay time
Real-power Load Sharing
The real-power load sharing function lets two or more CGCM-DLR units or
other compatible generator control devices (such as the Line Synchronization
Module™, bulletin number 1402-LSM) to load the generators under their control
such that each generator develops the same per unit output. A 0...5V DC signal is
developed proportional to the per unit kW output of the generator and fed to the
load sharing terminals through an internal resistor. The configurable full-scale
voltage corresponds to the rated generator kilowatts. The load sharing output is
updated every 50 ms.
The load sharing terminals are connected in parallel (plus to plus, minus to
minus) with other compatible devices. If the CGCM-DLR unit generator is
more heavily loaded than the others, its developed load share voltage is higher.
Also, current flows out of the CGCM-DLR unit and into other devices on the
network. A more lightly loaded generator results in a lower load share voltage and
current flows into the CGCM-DLR unit.
The direction and magnitude of current flow is used to develop the Load Share
Error value the CGCM-DLR unit makes available to the host logic controller.
The host logic controller program can use this value to control the prime mover
governor and balance generator output with others in the system.
The CGCM-DLR unit exhibits two rates of change features, Limit and Rate that
work together to protect against an unstable system.
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
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