Deif SGC 420 User Manual page 47

occurs only when all the three phases fail. Upon Mains failure the genset only receives a Start command if one of following
conditions occur:
• Site battery voltage level is below its lower limits.
• Shelter temperature is above its upper threshold limits.
• If either of the above occur when source is partially healthy.
NOTE It is recommended to keep Mains monitoring enabled in this mode and to use the Shelter temperature only when Site
monitoring is enabled.
Automatic Mains Failure (AMF) mode
DG OFF
Mains unhealthy
Warm up
Warm up delay expired
DG ON
Mains healthy
Return to
Mains
Return to Mains delay expired
Engine
cooling
AMF mode is activated when Site monitoring, Cyclic and Exercise modes are disabled, and Mains monitoring is enabled.
If the mains is healthy, the genset remains in Stop mode. If the mains is unhealthy for longer than the Mains detect delay time, the
controller sends a Start command and the genset starts according to the Start sequence. When the genset loading voltage and
frequency are above the Minimum healthy thresholds, the Warm-up delay timer starts. At the end of the Warm-up delay, the Load
transfer delay starts and the genset latches.. Engine running hours increase while the genset runs. The running hours stop
increasing when a Stop command is received. During genset running mode, if the mains is found healthy, the Return to mains delay
timer starts. If the mains is found unhealthy during the Return to mains delay, the genset continues to run. At the end of the Return
to mains delay, if mains is still healthy, the genset contactor opens and the mains contactor latches after the Load transfer delay.
After opening the genset contactor, Engine cooling time starts. At the end of Engine cooling time, the controller initiates the Stop
sequence by giving the Stop command.
If the mains voltage recovers or any stop command or shutdown alarm occurs during the Crank time, the controller will not send a
start command. To start the genset again, all the alarms must be cleared manually.
NOTE AMF mode is only valid when Site monitoring, Cyclic and Exercise modes are disabled, and Mains monitoring is enabled.
USER MANUAL 4189341227A UK
Engine
cooling
Page 47 of 86