Allen-Bradley 1407-CGCM, User Manual, Page: 59 / 252

Rockwell Automation Publication 1407-UM001H-EN-P - November 2014
CGCM Unit Operation #HAPTER
The Rotating Diode fault is inhibited if the field current is less than
1.5 A DC or if the generator frequency is outside the range of 45…70 Hz.
0HASE2OTATION&AULT
The CGCM unit calculates the negative sequence voltage of the 3-phase
generator voltage sensing input. When the generator phase rotation is opposite to
the wiring rotation you configured, the level of the generator negative sequence
voltage increases to approximately 100%. The pickup value for this function is
fixed at 66%. When the pickup value is exceeded, timing is started. After a one
second delay a phase rotation fault is indicated. A phase rotation fault is also
indicated when a phase loss condition occurs. If this fault occurs, tag
PhRotFlt = 1 in the Scheduled Read table.
'ENERATOR/VERCURRENT6
A generator over-current fault occurs when generator current exceeds the
generator over-current function’s setpoint. You configure over-current protection
by selecting a time characteristic curve, an over-current setpoint, a time dial
setting and a voltage restraint setpoint. The over-current function meets
ANSI/IEEE C37.112.
See Appendix A for a list of available curves and more detail.
If this fault occurs, tag Ovr_I_Flt = 1 in the Scheduled Read table.
3YNCHRONIZING
The CGCM unit monitors the generator and bus voltage sensing inputs to
provide synchronization between the generator and either of two buses. The
CGCM unit provides voltage, phase and frequency error parameters, and a
breaker close permissive signal, to its host Logix controller. This lets the
controller control the prime mover, achieve phase synchronization, and voltage
matching.
The CGCM unit can also provide synchronization between two busses by
measuring appropriate synchronization parameters. For synchronizing between
two busses, substitute the term second bus for generator in the discussions that
follow.
When synchronizing a system between systems with differing metering
configurations, the synchronization configuration must account for any phase
shift or voltage differences between the two systems. For example, when
synchronizing a three-wire (delta) generator to four-wire (wye) bus system, the
synchronization configuration must take into account the 30° phase shift
between line-to-line and line-to-neutral voltage.