104 Program features
for informing the PFC logic that a motor is not available (for example due to
maintenance or manual direct-on-line starting).
Soft pump and fan control (SPFC)
The Soft pump and fan control (SPFC) logic is a variant of the PFC logic for pump
and fan alternation applications where lower pressure peaks are desirable when a
new auxiliary motor is to be started. The SPFC logic is an easy way to implement soft
starting of direct on line (auxiliary) motors.
The main difference between traditional PFC and SPFC logic is how the SPFC logic
connects auxiliary motors on-line. When the criteria for starting a new motor is fulfilled
(see above) the SPFC logic connects the drive controlled motor to the supply network
in a flying start, that is, while the motor is still coasting. The drive then connects to the
next pump/fan unit to be started and starts controlling the speed of that one, while the
previously controlled unit now is connected directly on line through a contactor.
Further (auxiliary) motors are started in a similar manner. The motor stopping routine
is the same as for the normal PFC routine.
In some cases SPFC makes it possible to soften the start-up current while connecting
auxiliary motors on-line. Lower pressure peaks on the pipelines and pumps may be
achieved as a result.
Settings
• Parameter 96.04 Macro select (macro selection)
• Parameter group 10 Standard DI, RO (page 159)
• Parameter group 40 Process PID set 1 (page 278)
• Parameter groups 76 PFC configuration (page 318) and 77 PFC maintenance
and monitoring (page 323).
Timed functions
See parameter group 34 Timed functions. Settings
Parameter group 34 Timed functions (page 255).
Motor potentiometer
The motor potentiometer is, in effect, a counter whose value can be adjusted up and
down using two digital signals selected by parameters 22.73 Motor potentiometer up
source and 22.74 Motor potentiometer down source.
When enabled by 22.71 Motor potentiometer function, the motor potentiometer
assumes the value set by 22.72 Motor potentiometer initial value. Depending on the
mode selected in 22.71, the motor potentiometer value is either retained or reset over
a power cycle.
ACS580 FW.book Page 104 Wednesday, September 21, 2016 9:48 PM
To Next Page
Loading...
