Specifications - City of Montpelier, Vermont

Title:Montpelier District HeatingCity of Montpelier, VT16480 – MOTOR CONTROLLERSIssue Date:September 28, 2012Page #:6 of 12programmable relay output for customer use to indicate the loss ofreference condition.c. The VFD’s shall utilize plain English digital display (codenumbers and letters are not acceptable). The digital display shallbe a 40character (2 line x 20 characters/line) LCD display. TheLCD shall be backlit to provide easy viewing in any lightcondition. The contrast should be adjustable to optimize viewingat any angle. All setup parameters, indications, faults, warningsand other information must be displayed in words to allow the userto understand what is being displayed without the use of a manualor crossreference table.d. The VFD’s shall utilize preprogrammed applications specificallydesigned to facilitate startup. The Application Macros shallprovide one command to reprogram all parameters and customerinterfaces for a particular application to reduce programming time.e. The VFD shall have the ability to automatically restart after anovercurrent, overvoltage, under voltage, or loss of input signalprotective trip. The number of restart attempts, trail time, and timebetween reset attempts shall be programmable. If the timebetween reset attempts is greater than zero, the time remaininguntil reset occurs shall count down on the display to warn anoperator that a restart will occur.f. The VFD shall be capable of starting into a rotating load (forwardor reverse) and accelerate or decelerate to set point without safetytripping or component damage (flying start).g. The VFD shall be equipped with an automatic extended power lossridethrough circuit which will utilize the inertia of the load tokeep the drive powered. Minimum power loss ridethrough shallbe onecycle, based on full load and no inertia. Removing powerfrom the motor is not an acceptable method of increasing powerloss ridethrough.h. The customer terminal strip shall be isolated from the line andground.i. The drive shall employ three current limit circuits to provide tripfree operation: The Slow Current Regulation limit circuit shall beadjustable to 125% (minimum) of the VFD’s variable torquecurrent rating. This adjustment shall be made via the keypad, andshall be displayed in actual amps, not as percent of full load.j. The Rapid Current Regulation limit shall be adjustable to 170%(minimum) of the VFD’s variable torque current rating.k. The Current Switchoff limit shall be fixed at 255% (minimum,instantaneous) of the VFD’s variable torque current rating.MOTOR CONTROLLERS 16480 6