Himoinsa CEM7 - Page 44

CEM7 CONTROL UNIT ALARMS | PAGE 44
MINIMUM GENSET FREQUENCY
The CEM7 control unit's minimum genset frequency alarm is associated with the
condition that the frequency generated by the genset is below the minimum
frequency limit set (Thresholds table, parameter 6).
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 the second phase no signal is detected either,
a measurement is then taken of the third phase frequency. Detection of the
minimum genset frequency alarm is set by default (Alarms table, parameter 64)
to be activated under nominal engine conditions.
A minimum genset frequency alarm can be associated a debounce time (Alarms
table, parameter 65) during which the frequency must be kept below the
maximum threshold limit set (Thresholds table, parameter 6). The minimum
genset frequency alarm is set by default (Alarms table, parameter 66) to perform
a stop of the engine with cooling.
UNEXPECTED STOP
The CEM7 control unit's unexpected stop alarm is generated if, while the engine
is running, all the running engine conditions are no longer detected (Table
Regulations, parameters 19-22).
STOP FAILURE
The stop failure alarm of the CEM7 control unit goes off if after a time has
elapsed (Times table, parameter 36) after the engine has been ordered to stop,
not all the conditions programmed for the detection of a stopped engine have
been met (Regulations table, parameters 19 to 22).
In the event the stop failure alarm has been disabled (Alarms table,
parameter 70), after waiting a maximum of 15 seconds for stopped engine
conditions, the control unit considers that the engine is stopped.
To detect the engine as stopped, all the stop conditions must be detected for a
set period of time (Alarms table, parameter 71).
SHORT CIRCUIT
The CEM7 control unit's short circuit alarm is associated with the condition that
the measurement of the RMS current is above the maximum short circuit limit
set (Thresholds table, parameter 8).
The phases which are evaluated for the detection of the short circuit alarm are
selected depending on the conguration of the installation phases (Thresholds
table, parameter 1):
• In a single phase conguration phase 1 is tested.
• In a two-phase conguration phases 1 and 2 are tested.
• In a three-phase conguration with neutral or three-phase without
neutral phases 1, 2 and 3 are tested.
Detection of the short circuit alarm is set by default (Alarms table, parameter 58)
to be activated: Under nominal engine conditions.
The short circuit alarm is set by default (Alarms table, parameter 60) to perform
a stop of the engine with cooling.
MINIMUM GENSET VOLTAGE
The CEM7 control unit's minimum genset voltage alarm is associated with the
condition that the measurement of the genset's RMS voltage is less than the
minimum voltage limit set (Thresholds table, parameter 3).
The phases which are evaluated for the detection of the minimum 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 minimum genset voltage alarm is set by default (Alarms table,
parameter 61) to be activated under nominal engine conditions. A minimum
genset voltage alarm can be associated a debounce time (Alarms table,
parameter 62) during which the voltage must be kept below the minimum
threshold limit set (Thresholds table, parameter 3). The minimum genset voltage
alarm is set by default (Alarms table, parameter 63) to perform a stop of the
engine with cooling.