Himoinsa CEM7 - Programmable Alarm

CEM7 CONTROL UNIT ALARMS | PAGE 41
MAXIMUM GENSET FREQUENCY
The CEM7 control unit's maximum genset frequency alarm is associated with the
condition that the frequency generated by the genset is above the maximum
frequency limit set (Thresholds table, parameter 5).
The measurement of genset frequency is carried out on the rst phase. If in that
phase no signal is detected, the frequency measurement is then carried out on
the second phase. Likewise, if in that phase no signal is detected either, the
frequency measurement is then carried out on the third phase.
Detection of the maximum genset frequency alarm is set by default (Alarms
table, parameter 37) to be activated under nominal engine conditions.
A maximum genset frequency alarm can be associated a debounce time (Alarms
table, parameter 38) during which the frequency must be kept above the
maximum threshold limit set (Thresholds table, parameter 5). The maximum
genset frequency alarm is set by default (Alarms table, parameter 39) to perform
an immediate stop of the engine.
INCORRECT GENSET PHASES SEQUENCE
The CEM7 control unit’s incorrect genset phases sequence alarm is associated
to the fact that the genset voltage inputs of each phase are in order (phases 123
for direct conguration of sequences —value 0, Regulations table, parameter
34— or phases 321 for inverse conguration of sequences —value 1,
Regulations table, parameter 34—).
The incorrect genset phases sequence alarm is only enabled when the control
unit is congured to work three-phase with neutral or three-phase without neutral.
Detection of the incorrect genset phase sequence alarm is set by default (Alarms
table, parameter 40) to be activated: From the rated condition of the engine.
An incorrect genset phases sequence alarm can be associated a debounce time
(Alarms table, parameter 41) during which an incorrect order in the maximum
genset voltages must be detected.
The incorrect network phases sequence alarm is set by default (Alarms table,
parameter 42) to: Stop the engine with cooling of the engine.
GENSET VOLTAGE ASYMMETRY
The CEM7 control unit's genset voltage asymmetry alarm is associated with the
fact that the difference between any two RMS voltages between genset voltage
phases (VG12, VG23 or VG31) exceeds the maximum asymmetry limit
programmed (Thresholds table, parameter 4).
The voltage asymmetry alarm is activated only when the control unit is congured
to measure the voltage of three-phase with neutral or three-phase without
neutral. Detection of the genset voltage asymmetry alarm is set by default
(Alarms table, parameter 31) to be activated under nominal engine conditions.
The CEM7 control unit's genset voltage asymmetry alarm can be associated a
rebounce time (Alarms table, parameter 32) during which the difference between
any two values of genset phase voltage (VG12, VG23 or VG31) should be kept
above the maximum limit set (Thresholds table, parameter 4). The genset voltage
asymmetry alarm is set by default (Alarms table, parameter 33) to always perform
a stop of the engine with cooling.
MAXIMUM GENSET VOLTAGE
The CEM7 control unit's maximum genset voltage alarm is associated with the
condition that the measurement of the genset's RMS voltage is above the
maximum voltage limit set (Thresholds table, parameter 2).
The phases which are evaluated for the detection of the maximum genset voltage
alarm are selected depending on the conguration of the installation phases
(Thresholds table, parameter 1):
• In a single phase conguration voltage V1N is tested.
• In a two-phase conguration voltage V12 is tested.
• In a three-phase conguration with neutral or three-phase without
neutral, phases V12, V23 and V13 are tested.
Detection of the maximum genset voltage alarm is set by default (Alarms table,
parameter 34) to be activated under nominal engine conditions. A maximum
genset voltage alarm can be associated a debounce time (Alarms table,
parameter 35) during which the voltage must be kept above the maximum
threshold limit set (Thresholds table, parameter 2). The maximum genset voltage
alarm is set by default (Alarms table, parameter 36) to perform an immediate stop
of the engine.