Thanks again Prr and John,
So first day on the shop floor today for me in the motor rewinds place , very good , fixed up a few multimeters that were troublesome, got a fluke ammeter clamp and another cheaper but well used meter going . Then I was allowed onto a job for a customer , some kind of of induction coils belong to the technical college ,mains powered , had a bridge rectifier with a bad solder joint on it ,they had assumed the coil was faulty . Two minute solder job and back up working ,so boss was impressed , he kinda said I fixed it too quick . I have the entire stock of Farnell to pick parts for repairs from , really very little electronics at all though, Electromecanical for the most part , I was shown how to break down and extract the the coils on a motor and prep it for re-stuffing with new copper ,all the really dirty stuff is done in the oven room ,its like hell in there ,wire brushes&diesel , compressed air ,sharp cold chissels and ball peen hammers , gunky ovens that stink ,sh!t,muck and dust . A sample of the wires is always taken from the old motor , the insulation is blow torched off a section of wires ,then the gauge is cross checked . One of the coil sections is reserved for counting also .
I think a serious look at the electrics to the benchs is in order , They guys routinely use a 'suicide lead' to spark the windings on the motor for continuity ,its arranged with a light bulb in series and a couple of bars from electric heaters can also be switched in to drop volts . The section with the bulb and load sharing resistors is seperate from direct mains connection but still no iso transformer , which really would make a lot of sense here, probably a good plan is all the benches are fitted with Isolation transformers as soon as possible .and I said that to the boss . Theres just no need to be standing a the chance of full direct mains across your body ,even though the floor is well insulated , a ground lifted mains supply through a transformer would seem to be the correct way to do it ,even centre tapped to ground would be a big improvement , sometimes the windings of a motor short to case ,which could catch someone out easily ,with a floating mains supply only way you could concievable get shocked is by grabbing both live and neutral wires/terminals at the same time .
In the longer run its probably better for me to concentrate on the electronic side of things ,but Im being presented an oppertunity to learn the trade of motor winding from the ground up while picking up technicians rates for any electronic stuff I do .
Star or delta configuartions depending on threephase or normal supply, the windings are divided into sections and loaded into the housing seperately , brazed together and insulated . The windings are brought out to a six terminal block ,which can be configured for single or three phase . the more rpm the more sections to the coil . Loading the coils is preceeded by forming special paper insulators which are inserted into the coil slots first ,then after another folded V shaped paper strip in used to lock the copper into its slot and provide more insulation to case/ground. The sheer range of materials used is astonishing ,everything a transformer winder could desire ,big boxes of off cuts of everything .Some interesting caps ,high value motor start and runs ,40,50,60 ,70 ,80 uf ,250volts ac, crazy cheap as you said Prr, if size isnt an issue well capable of suplementing or replacing electrolytics in tube designs.
Got asked by the boss for my bank account details ,and invited back down Friday ,so off to a good start .