Liquid Starter

Try these folks, they rebuild these units.

OSSETT INDUSTRIAL PROJECTS LTD
Rear Works,
South Parade,
Ossett,
West Yorkshire,
WF5 0EF
UK

The starter sounds as if it would be the same Allen West model I've worked on, on both crushers and fans.

Second bit first, the contact springs have an insulated washer with a shoulder on it, top & bottom of each spring. These stop current flowing through the spring and weakening it. I made new ones out of polypropylene rod the original tuffnel one had all disintegrated.

On one of the fans (almost the same spec as yours, 1750V instead of 1700V) I installed 3 Telemecanique 315A 3-pole contactors, one contactor per phase. The reason for separating the phases to individual contactors is I didn't want 1750V on adjacent contacts rated at 1000V. The reason for choosing the 315A contactors was simple, we'd got two in stores as spares for other machines, so a bit of creative accountancy meant I'd got 2/3^rds of what I needed cheap! If ever you've watched the rotor current you will see it only caries FLC for 1/3^rd of the time. Each contactor @ 900A is well on top of the job. I retarded the final close of the original mechanical contacts and set the contactors to close just before them. It reduced the final motor starting current "kick" to about 180% FLC, well below what it had been. To be honest I never knew what the final kick was before, the subs 11KV incomer ammeter went off scale @ 400A!

To mount the contactors I acquired a cabinet that was the full width of the starter and about half as high, by cutting a hole in the back of the cabinet I mounted it on the inspection cover bolts. (Don't ask how I "acquired" the cabinet, that was another bit of creative accountancy).

What ever you do retain the mechanical contacts in the event of a contactor failure the drive will then keep running.

It's great when you manager assists in the creative accountancy department. He was doing it for a reason, to build up a case to get rid of me! We'd had major differences, he thought the scheme was mad and was waiting for it to go wrong. On the day of the first trial he was on hand to gloat and had invited along one of the directors to see my downfall. After the first trial run the director told me not to bother with a 2^nd, just put it in to permanent service.

I'd done a lot of research in to this with assistance from Telemecanique's technical bods. I'd tested a contactor that had been in service so it was dirty and horrible at 5000V DC with no problems. The contacts only had to make load, not break it.

I walked away smelling of roses, my boss stank a bit.