Chapter 6 – Parameters
ACH 500 Programming Manual 6-51
1+1 motors 50.0%
1+2 motors 33.3%
1+3 motors 25.0%
For example: if the values of the parameters are:
Nbr of lag motors (40.2.17) = 2
Alternation level (40.2.19) = 25%
Max frequency (20.1.2) = 51 Hz
the alternation takes place at 38.3 Hz (25%/33.3% x 51 Hz) if the following
conditions are true:
• Alternation interval time has elapsed,
• Actual value is below the set alternation level,
• Minimum one lag motor is not running, and
• The ACH 500 is not running at a preset speed (DI/param., Group 10.3).
When all the conditions are valid, PFC stops all motors, changes the order of
the motors, and starts the motors using the new start order. The starting order
cannot be changed externally.
The start order and the elapsed run time remain in the ACH 500 memory
during a power interruption.
Note: If only the regulated pump is used, cancel the alternation operation by
setting Parameter 40.2.18 (Alternation Interv.) to 00 h 00 min. This
releases relay outputs RO1 to RO4 for other use.
20 INTERLOCKS
ON/OFF
Digital inputs can be used as interlocks for the connected motors. A contact
from the disconnect at each motor is brought to a digital input. If a motor is
taken out of service, the ACH 500 will skip that motor when it is needed and
select the next available pump. If this parameter is set to ON, DI2 DI3, and
DI4 are reserved for the interlocks. The I/O extension board must be ordered
to use this function. If this function is set to OFF, the digital inputs are
available for other functions.
If an interlocking function is in use and one of the interlocking signals
disappears while the motors are running, the ACH 500 will stop and a
corresponding output relay (RO1 to RO4) will release and stop the respective
motor. If other motors are available, PFC connects one of those instead and
starts the ACH 500 again.
21 ERROR VALUE INV.
NO/YES
This parameter allows you to invert the Error Value (and thus the operation of
the PI-Controller). Normally, a decrease in Actual Signal (Feedback) causes
an increase in drive speed. If a decrease in Actual should cause a decrease in
speed, set Error Value Invert to YES.
22 ACTUAL 1 INPUT
AI1 OR AI2
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