Rockwell Automation 1407-CGCM Combination Generator Control Module - Manual (Page 39)

Rockwell Automation Publication 1407-UM001G-EN-P - April 2013 39
CGCM Unit Operation Chapter 3
The CGCM unit uses voltages measured through the generator voltage sensing
inputs for generator voltage, VAR and/or power factor regulation, kW and kVAR
load sharing, synchronization, metering, and protection. The inputs accept
signals with up to 40% Total Harmonic Distortion (THD) and are connected for
single-phase and 3-phase applications. The generator voltage inputs are internally
scaled by the CGCM unit according to its transformer configuration settings.
Generator voltage sensing inputs are labeled V Gen A, V Gen B, V Gen C, and V
Gen N.
Bus Voltage Sensing Inputs
Voltages measured through the bus voltage sensing inputs are used for generator
to bus synchronizing. The CGCM unit senses bus voltage through VTs.
Depending upon the number of busses and the type of synchronizing required,
there is one or two sets of bus sensing transformers. If dual bus synchronizing is
required, the sensing transformer configuration is limited to single-phase. In a
single breaker system the inputs are connected in either single-phase or 3-phase
configurations. The inputs accept signals with up to 40% THD. The bus voltage
inputs are internally scaled by the CGCM unit according to its transformer
configuration settings.
Bus voltage sensing inputs are labeled V Bus A, V Bus B, V Bus C, and V Bus N.
Generator Line Current
The CGCM unit senses generator current through current transformers installed
on the generator output leads.
Current measured through the line current inputs is used for metering purposes,
regulating generator vars, regulating generator PF, real power load sharing, and
for protection purposes; and is required for operation in AVR Droop, PF, and
VAR operating modes. Line current inputs are galvanically isolated via CTs
internal to the CGCM unit. The CGCM unit accepts either 1 A or 5 A current
inputs wired to the corresponding input. Line current inputs are labeled I1(+)1
A, I1(+)5 A, I1(-), and so forth.
Cross-current
The CGCM unit senses reactive differential current through properly connected
current transformers typically installed on the B-phase output leads of each
paralleled generator.
See Typical Cross-current CT Locations and Polarity on page 34 for more
information.
Line current inputs are galvanically isolated via CTs internal to the CGCM unit.
The CGCM unit accepts either 1 A or 5 A current inputs. The cross-current
input terminals are labeled ID(+)5A, ID(+)1A, and ID(-).