INFO
The table above is only for Single DG application!
In the AGC there are two different alarms concerning the phase sequence error, and hereby two different fail classes. The alarm for
phase sequence error and phase rotation is set in parameter 2150. The parameters are described in the table below:
Parameter Menu text Description
2151 Output A Relay output if the AGC detects a phase sequence error on the genset voltage terminals.
2152 Output B Relay output if the AGC detects a phase sequence error on the genset voltage terminals.
2153 fail class
Determines how the AGC reacts if the AGC sees a phase sequence error on the genset voltage
terminals.
2154 Rotation
Determines the rotation of the voltages the AGC is measuring on. This is both for the genset voltages and
mains voltages.
2155 Output A
Relay output if the AGC detects a phase sequence error on the mains voltage terminals. Since there is no
output B on this alarm, it has been configured that output B is the same as output A.
2156 fail class Determines how the AGC reacts if the AGC sees a phase sequence error on the mains voltage terminals.
Example
In a Single DG application with GB and MB (like the application shown previously), the parameters are set like in the table below:
Parameter
Menu text Description
2151 Output A Not used
2152 Output B Not used
2153 fail class Trip+Stop
2154 Rotation L1L2L3
2155 Output A Not used
2156 fail class Trip MB
INFO
An alarm is activated if no relay output A/B is selected. Do not chose Limits/Limit relay if you want that an alarm is raised
together with a relay output A/B.
If the controller is set to Load Take Over (LTO) and the start signal is given the genset will start up. If there have been performed a
service of the alternator, and two of the phases have been switched when the alternator has been assembled again, the AGC will
now discover a phase sequence fail. Since this is on the genset voltage terminals, the fail class set in parameter 2153 will be used.
The fail class is set to Trip+Stop, which will trip the breaker (If the breaker is not closed, the controller will not send a trip signal), and
then afterwards go into the stop sequence. If the alarm is acknowledged, the genset will start up again, if the start signal is still
present.
In this plant there could be a situation where there is some changing in the grid. If the grid company is coupling in the grid, and the
phase sequence in changed on the grid connection, and the Mains fail timers does not react on the small blackout, the fail class in
parameter 2156 will be used. At the moment there is a phase sequence error on the mains voltage terminals, and the fail class is
Trip MB. When the MB is tripped, the genset is started, since there is a trip alarm MB, and load does not have any power at the
moment. In the same plant it can be possible to that a service of the transformer is going to happen. To test the Automatic Mains
Failure (AMF) sequence, the technician removes the fuses, and the AGC will then discover the voltage is not present and afterwards
start up the genset and take the load. When the technician is assembling the transformer again he accidentally switches two
phases. When the fuses is set into place again, the AGC will discover a phase sequence error on the mains voltages, and by this it
will still keep running, until the phase sequence has been fixed.
DESIGNER'S HANDBOOK 4189341275A EN Page 66 of 196
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