156 Program features
motors. The main difference between traditional PFC and SPFC is the way SPFC
connects auxiliary motors on-line.
SPFC connects auxiliary motors online with a flying start, while the motor is still
coasting. Thus, in some cases SPFC makes it possible to soften the start-up current
while connecting auxiliary motors on-line. This is why lower pressure peaks on the
pipelines and pumps may also be achieved. Connection sequence and powering
routine of auxiliary motors in SPFC is explained more detailed in the diagram. The
motor stopping routine follows always the normal PFC routine.
SPFC powering routine
The diagram below illustrates the SPFC powering routine.
1. At start, relay RO 1 is closed and motor 1 is connected to the drive output.
2. The drive waits for the time specified by parameter 8122 PFC START DELAY to
ensure that the contactor (RO 1) has stabilized and then starts modulating from
zero speed. Motor 1 is the speed regulated motor.
3. When the drive output frequency f
out
rises over the start frequency (8109 START
FREQ 1), the start delay for the auxiliary motor (8115 AUX MOT START D) is set.
4. When delay 8115 has elapsed, the drive coasts to stop and relay RO 1 is opened
(motor 1 is disconnected from the drive output).
5. The drive waits for 8122 PFC START DELAY to ensure that the contactor (RO 1)
has stabilized.
6. After delay, 8122 RO 2 is closed and motor 2 is connected to the drive output as
the new speed regulated motor.
8115 AUX MOT START D
8122 PFC START DELAY
RO 1 / Motor 1
RO 2 / Motor 2
f
out
Start
Motor 1 is speed reg. motor
Motor 2 is speed reg. motor
Motor 1 is aux. motor
1
2
3
4
6
5 7
8
t
8109 START
FREQ 1
8122 PFC START DELAY
8122 PFC START DELAY
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