Actual signals and parameters 273
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 drive output – the speed regulated motor.
The starting order of the other motors rotates.
The Autochange function requires:
• external switch gear for changing the drive’s output power
connections
• parameter 8120 INTERLOCKS > 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 drive always coasts to stop when Autochange is
performed.
50.0%
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 switch gear connects this motor
to the drive power output.
• Delays motor start for 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.
All parameters
No. Name/Value Description Def/FbEq
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