POCO has nuisance transformer fuse melts

[11bgrunt]

Large car wash will experience random outages caused by a POCO overhead transformer fuse melting. This happens a few times a year.
I am adding a voltage recorder on the secondary this week.
The service is 400A, 480Y/277. POCO has three 100kVA transformers fused 15T on 24.9Y/14.4kV.
The general rule is this fuse melts at X2 the rating after five minutes. This time only one transformer fuse melted but have seen all three melted at the same time.
That math is 432kVA at least.
The attendant said the large drying fans were running, turned off and when they restarted, the fans were still turning. That is when the POCO fuse melted.
A thought I had was the turning motor acts a generator and when the contactor closes to start that motor again, the voltages are not in synch.
The first thought was a turning motor would reduce inrush because it was already turning.
The attendant said they have a similar random issue at another one of their locations.

Possible?
A motor restart time delay has worked on turbine water well sites that melted POCO transformer fuses.
Thanks,

 

[zbang]

I'd be more interested in current recordings.

What's the usual running load of the whole place?
What type and size of motor(s)?
How long are the fans off before turning back on and blowing the fuse? (I'm assuming across-the-line starters and basic induction motors.)
How long does it take for them to coast to a stop? Can anything cause them to spin backwards? When the fuse blows, did they all start at the same time? Do they ever all start at the same time?

IIRC submerged well pumps (I assume that's what you mean) can a special case as they can spin backwards until the water column above is empty.

 

[ptonsparky]

Fans running backwards would be an issue. Submerged well pumps should have a check valve somewhere unless they are pumping from a holding tank.

Proper Logic would prevent all items from auto restarting at the same time.