Basic Documentation

Disclaimer: These are sample drawings and sequences. Designers are responsible for
finalizing the content for their particular projects.
point sources, a sleep mode function, PID set point boost and a feed forward
function to improve process response.
18. Run permissive circuit shall be included for damper or valve control.
19. The customer terminal strip shall be isolated from the line and ground.
20. The drive shall employ current limit circuits to provide trip free operation:
a. The Slow Current Regulation limit circuit shall be adjustable to 150%
(minimum) of the VFD's normal duty current rating. This adjustment shall
be made via the keypad, and shall be displayed in actual amps, and not as
percent of full load.
b. The Current Switch-off limit shall be fixed at 180% (minimum,
instantaneous) of the VFD's normal duty current rating.
21. The overload rating of the drive shall be 110% of its normal duty current rating for
1 minute in every 10 minutes.
22. The VFD shall have integrated harmonic filters in the DC link.
23. The VFD shall incorporate a Multi-Pump Controller Wizard capable of controlling
up to five motors. The VFD is connected to one motor which is the "regulating"
motor connecting and disconnecting the other motors to/from the mains, by
means of contactors controlled with relays to maintain a given set point. This
function shall have an auto-change function for changing starting order of pumps
which allows for equal wear on all pumps.
24. The VFD shall be capable of sensing a loss of load (broken belt / no water in
pump) or high current mechanical sensing failure, and signal the loss of load
condition. The drive shall be programmable to signal this condition via a keypad
warning, relay output and/or over the serial communications bus.
25. The VFD shall include a motor switch ride through and is enabled or disabled
through the keypad. This feature allows the motor maintenance switch to be
opened and closed without stopping or tripping the drive.
G. All VFDs to have the following adjustments:
1. Three (3) programmable critical frequency lockout ranges to prevent the VFD
from operating the load continuously at an unstable speed.
2. A custom PID preset for HVAC & fluid systems, allow a pressure or flow signal to
be connected to the VFD, using the microprocessor in the VFD for the closed
loop control. The VFD shall have 100 mA of 24 VDC auxiliary power and be
capable of loop powering a transmitter supplied by others. The PID setpoint shall
be adjustable from the VFD keypad, analog inputs, digital inputs, or over the