D
I have a project which requires to keep a number of VSD Driven exhaust fans running for 3 minutes in the event of power failure. 3 minutes is the maximum time that the Generator need to cut in. The VSD Drives we are using are :- Allen Bradley 13361 PLUS II Adjustable Frequency AC Drives or equal Input is 480 VAC, and Fan is rated at 175 HP. We expect to have 4 x 175HP taking DC power from a common battery bank(3 run + 1 standby). The Battery bank VDC will be fed to the VSD DC BUS probably through a diode/isolation switch, transistors. In designing the circuit, some considerations we have thought of are :- - Calculation of DC Bank Battery Power rating - Calculation of Discharge Voltage to keep within the DC BUS +/- Tolerance during the 3 mins - Protection against regeneration effect from the DC bus feeding back to the Battery Bank - Consideration of Isolating the Batteries when it is being charged as charging voltage will probably be higher than the DC BUS - Speed of Detection of Power Failures, or DC BUS LOSS etc - Cutting out the battery bank if power returns before the 3 mins is up - Prevent further discharge until the battery is charged up again. - Design for disabling the battery circuit, if the VSD is in the OFF position - Interlock to prevent the Battery Bank from starting up the VSD on black start etc... Anybody out there with experience in putting together a Battery Backup RIDE THROUGH for VSD ? or can recommend a company which provide such products or services ? Any importants, or comments will be welcome. Thanks Derek Chan