ETO Cranes With Active Front End (AFE) VFD

"No" to both questions.

1) Yes and even more if the VFD has a regenerative system. In fact the crane applications where the frequent starts and stops are there the VFD might score by - putting less stress on motor as well as improving the efficiency of the system.

2) No

There are two kinds of AFE drives, or rather two operating modes, and some VFDs do not provide both at the same time, so you answer to Q1 is "it depends". If you have an AFE drive that is intended to operate such that the harmonics are reduced through use of the AFE, then typically that means it will NOT be providing regenerative braking control. It is only through regen braking that you can reduce your energy costs. You also must keep in mind that this may not actually SAVE energy however, because if your utility does not support reverse flow and you have no other loads on at the same time, you save nothing.

The answer to Q2 is an unequivocal NO! If the power fails, you have no brakes! But you can use the AFE on a regular basis to reduce wear on the brakes and only set them as "parking brakes". They will last virtually forever then.

It is somewhat disturbing that here is a proposal to modify a piece of equipment that is safety-critical in a way that the original equipment manufacturer is unaware of or has discounted as inappropriate, just to save a kWh or two. What it does, if carried out, is give the facility's insurance company a way of wriggling out of settling any liability claim for damages as a result of the modified equipment causing damage to the facility, loss of product, injury or fatality.

May the modifier accept the full consequences of this action.

Dear Mr. PWSlack

I understand your concern, believe me here my main intention is to get the energy saving but not at the cost of safety.

We are trying to propose this at a customer who is having around 300 Nos EOT cranes.