I am helping on a project with VFD controlled, 100HP fan motors and I do not have too much experience with VFD installations.
480/3ph
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this will be set in V/hz mode for ramp up.
1. how can I determine current draw for the configured ramp up time?
2. can you guys also provide some input in important things to consider when designing VFD control?
Thanks!
As
petersonra has said, it is a fairly straightforward application.
In my experience, the usual reason for using a VFD on a fan is for energy savings. If you can reduce the speed by 10% and still get enough airflow, the energy consumption drops by 30%.
A couple of points from that.
The speed demanded is likely to be a signal from the system in which the VSD is being used. Maybe the project engineer or specification can provide detail. Possibly it will be 4-20mA and most VFDs have analogue input capability.
The second point from that is about speed range. Typically, fans on VFDs don't need to run much below 70% of rated speed so the minimum operating speed of the VSD may have to be set accordingly.
A few other points in no particular order.
The motor ought to be rated for VSD operation. That's rather important.
The length of the conductor run from VSD to motor maters. A long run may require filters. The VSD installation manual should have information on this.
How the conductors are arranged is also important. I'm from a different part of the world to you and we have different practices. We use steel wire armoured cable for installation. You might use conduit. I can't offer any advice on that other than don't stick signal cables in the same conduit as the motor power cables.