ABB ACS560, Firmware Manual

Page: 134 / 514

134 Control macros
Soft Pump and Fan Control (SPFC) macro
The Soft Pump and Fan Control (SPFC) logic is a variant of the PFC logic for pump
and fan alternation applications where lower pressure peaks are desirable when a
new auxiliary motor is to be started. The SPFC logic is an easy way to implement soft
starting of direct on line (auxiliary) motors.
In SPFC all the pumps are auxiliary pump and get connected to Direct On Line (DOL)
or drive as and when required. In PFC only primary pump is connected to the drive.
In SPFC logic the auxiliary pumps are connected as follows:
1. As the expected flow rate/demand increases, the speed of auxiliary pump 1
increases accordingly. When the auxiliary pump reaches the start speed ( 76.30 )
and exceeds the start delay ( 76.55 ), the drive connects the drive controlled motor
(auxiliary pump 1) to the supply network in a flying start, that is, while the motor is
still coasting.
2. The drive then connects to the auxiliary pump 2 and starts controlling the speed.
3. The auxiliary pump 1 is connected DOL through a contactor.
4. Further auxiliary motors, if connected, are started in a similar manner. The motor
stopping routine is the same as for the normal PFC routine.
5. In some cases SPFC makes it possible to soften the start-up current while
connecting auxiliary motors on-line. Lower pressure peaks on the pipelines and
pumps may be achieved as a result.
Note: The SPFC is supported in external control location EXT2 only. EXT1 can be
used for the manual control of pump 1.
The below timing diagram explains how and when an auxiliary pump is connected
with the SPFC logic.