Basic Documentation

Disclaimer: These are sample drawings and sequences. Designers are responsible for
finalizing the content for their particular projects.
16. If the input reference (0/4-20mA or 0/2-10V) is lost, the VFD shall give the user
the option of either (1) stopping and displaying a fault, (2) running at a
programmable preset speed, (3) hold the VFD speed based on the last good
reference received, or (4) cause a warning to be issued, as selected by the user.
The drive shall be programmable to signal this condition via a keypad warning,
relay output and/or over the serial communication bus.
17. The VFD shall include two-zone PID controllers that allow the drive to maintain
PID control from two separate feedback signals. VFD shall include two PID set
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.
D. All VFDs to have the following adjustments: