ABB ACQ550-U1-011A-6 User Manual Download

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ACQ550-U1 User’s Manual

169

8119

AUTOCHNG LEVEL

Sets an upper limit, as a percent of output capacity, for the autochange logic. When the output from the PID/PFC
control block exceeds this limit, autochange is prevented. For example, use this parameter to deny autochange when
the Pump-Fan system is operating near maximum capacity.

Autochange overview

The purpose of the autochange operation is to equalize duty time between multiple motors used in a system. At each
autochange operation:
• A different motor takes a turn connected to the ACQ550 output – the speed regulated motor.
• The starting order of the other motors rotates.
The Autochange function requires:
• External switchgear for changing the drive’s output power connections.
• Parameter 8120

INTERLOCKS

= value > 0.

Autochange is performed when:
• The running time since the previous autochange reaches the time set by 8118

AUTOCHNG

INTERV

• The PFC input is below the level set by this parameter, 8119

AUTOCHNG

LEVEL

Note:

The ACQ550 always coasts to stop when autochange is performed.

In an autochange, the Autochange function does all of the
following (see the figure):
• Initiates a change when the running time, since the last

autochange, reaches 8118

AUTOCHNG

INTERV

, and PFC

input is below limit 8119

AUTOCHNG

LEVEL

• Stops the speed regulated motor.
• Switches off the contactor of the speed regulated motor.
• Increments the starting order counter, to change the

starting order for the motors.

• Identifies the next motor in line to be the speed regulated

motor.

• Switches off the above motor’s contactor, if the motor was

running. Any other running motors are not interrupted.

• Switches on the contactor of the new speed regulated

motor. The autochange switchgear connects this motor to
the ACQ550 power output.

• Delays motor start for the time 8122

PFC

START

DELAY

• Starts the speed regulated motor.
• Identifies the next constant speed motor in the rotation.
• Switches the above motor on, but only if the new speed

regulated motor had been running (as a constant speed
motor) – This step keeps an equal number of motors running before and after autochange.

• Continues with normal PFC operation.

Starting order counter

The operation of the starting-order counter:
• The relay output parameter definitions (1401…1403 and

1410…1412) establish the initial motor sequence. (The lowest
parameter number with a value 31 (

PFC

) identifies the relay

connected to 1PFC, the first motor, and so on.)

• Initially, 1PFC = speed regulated motor, 2PFC = 1st auxiliary

motor, etc.

• The first autochange shifts the sequence to: 2PFC = speed

regulated motor, 3PFC = 1st auxiliary motor, …, 1PFC = last
auxiliary motor.

• The next autochange shifts the sequence again, and so on.
• If the autochange cannot start a needed motor because all

inactive motors are interlocked, the drive displays an alarm
(2015,

PFC

LOCK

• When ACQ550 power supply is switched off, the counter

preserves the current Autochange rotation positions in permanent memory. When power is restored, the
Autochange rotation starts at the position stored in memory.

• If the PFC relay configuration is changed (or if the PFC enable value is changed), the rotation is reset. (See the first

bullet above.)

Code Description

P 8118

PID output

P 8119

100%

P 8118

1PFC

2PFC

3PFC

4PFC