ABB ACS510-01 User Manual page 127

ACS510 User's Manual
Group 81: PFC Control
This group defines a Pump-Fan Control (PFC) mode of operation. The major
features of PFC control are:
• The ACS510 controls the motor of pump no. 1, varying the motor speed to control
the pump capacity. This motor is the speed regulated motor.
• Direct line connections power the motor of pump no. 2 and pump no.3...pump
no.6,etc (pump 4,5,6 need RO extension module OREL-01). The ACS510
switches pump no. 2 (and then pump no. 3...pump no.6, etc.) on and off as
needed. These motors are auxiliary motors.
• The ACS510 PID control uses two signals: a process reference and an actual
value feedback. The PID controller adjusts the speed (frequency) of the first
pump such that the actual value follows the process reference.
• When demand (defined by the process reference) exceeds the first motor's
capacity (user defined as a frequency limit), the PFC control automatically starts
an auxiliary pump. The PFC also reduces the speed of the first pump to account
for the auxiliary pump's addition to total output. Then, as before, the PID controller
adjusts the speed (frequency) of the first pump such that the actual value follows
the process reference. If demand continues to increase, PFC adds additional
auxiliary pumps, using the same process.
• When demand drops, such that the first pump speed falls below a minimum limit
(user defined by a frequency limit), the PFC control automatically stops an
auxiliary pump. The PFC also increases the speed of the first pump to account for
the auxiliary pump's missing output.
• An Interlock function (when enabled) identifies off-line (out of service) motors, and
the PFC control skips to the next available motor in the sequence.
• An Autochange function (when enabled and with the appropriate switchgear)
equalizes duty time between the pump motors. Autochange periodically
increments the position of each motor in the rotation – the speed regulated motor
becomes the last auxiliary motor, the first auxiliary motor becomes the speed
regulated motor, etc.
• The soft-start function ensures that all motors are started smoothly:When new
motors need to be started due to increasing pumping capacity need, they are
powered up by the drive as follows:
– When motor 1 reaches the AC powerline frequency, it is disconnected from the
drive and switched to direct on-line connection(with a slight delay in between).
– Motor 2 is connected to drive output. After a slight delay the motor speed is
increased to fulfil the pumping capacity needed.
– Motor 3...6 are sterted accoring to the same routine.
– The motor stopping routine follows always the normal PFC routine.
• This is the way PFC "Soft Start" controls the motors when starting new motors,
See the follow diagram:
– Drive is started and RO1 is closed. Modulation is not allowed.
Supplied from China by: Guangzhou Tofee Electro Mechanical Equipment Co., Ltd
Email: info@tofee.com.cn
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