On 6/21/2012 12:15 AM, Evan wrote: ...
Easy enough to say now... :)
Having set out for 20+ yrs since last used, it was already well gone as far as the wiring between boxes so...besides who'dda thunk there was anything unique going on, anyway?
Not agonna' happen... :) (Altho if there isn't something in the pile of other pieces-parts in the barn that makes it more convenient (haven't had time to dig through yet) I did locate a P&B relay at Newark for
Dust collector sounds better than DC voltage.
Motor start current is about 6x run current. Would be nice if the contactor had a HP rating.
As I understand the contactor it changes when the coil is deenergized. This circuit should work:
230 start | _____ 230 | | | /x__________o o___________________ coil ________| | / | | |_____C/ | | | _____ | | | | | | x__________o o________| | | | | | contactor | stop | | | | |_______________________________dust col ____|
Pulsed, more accurately...but on the deenergize cycle of that, yes.
...[original elided for brevity and Stop side of switch modified to reflect what is present]...
230 start | _____ 230 | | | /x__________o o___________________ coil ________| | / | | |_____C/ | | | | | | _____ | | | x__________o o________| | | | | | contactor | stop | | | | |_______________________________dust col ____|Yes, it would if the Start/Stop were both NO but the Stop is NC as represented above. That would leave the coil energized during run and no way to deenergize it.
The only way w/o a second relay I can see could work would be to simply use the START button as a cycle ON|OFF and forget STOP. (NB my followup earlier that mentions that after an overnight I went and looked at the other large box that I remembered only having the motor-protect fuses in it and "discovered" the missing relay there...inconvenient for my present purpose but explained the mystery of how the silo unloader worked previously.
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Taken from old silo unloader to use as second parallel from alternate location DC in shop...
240V coil relay, 240V 2hp-rated contacts of the mechanical spring type--load contacts a common and one open/one closed pair. Relay operates by momentary make/break--when cycled, the spring-loaded contacts switch positions rather than by being held by continuous load.Switch is manual pushbotton, START is NO, STOP is NC and one side of each are common.
The wiring on the unloader was so decrepit I didn't try to trace it out when salvaging pieces/parts but I'll be darned if I can figure out how Dad had this wired to work (but I know it did, I was around for years while still were using it and it was sitting there as was removed and parked).
I can see how to get the START to work, what I haven't got my head around is the STOP function since it breaks a contact instead of makes one to cause the relay coil to momentarily energize/release to flip the spring-loaded contacts...
I'll see if I can manage an ASCII pictogram here...
************************ When you turn the thing on, part of the current goes through the stop switch circuit and that current holds the contacts together with the electromagnet coil. You press stop and the circuit holding the magnet is broken, so the contacts come apart and no power goes to the machine or the holding coil.-- Jim in NC
On 6/21/2012 8:48 PM, Morgans wrote: ...
Not if the it is a pulsing relay...
The mystery has been resolved elsewhere in the thread...
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OK, I now know how it was done...as concluded earlier, I was overlooking/forgetting a key part and now it has come to me what that is...
This switch and relay were mounted on the unloader up _in_ the silo; normally, however, the whole point of the unloader was to avoid having to climb the silo every (cold winter, particularly :) ) morning and throw feed down manually. But, on occasion it would malfunction by digging in or somesuch and it was necessary.
The controls I've salvaged were therefore in parallel to the "real" motor starter on the ground and connected via the umbilical cord that went from the unloader down the silo chute to the ground. The rest of the control logic and power feed for the motors was there...
Mea culpa, sorry... :(
For my present purpose I've ordered a rated DPDT Form C from Mr Newark that'll work as desired as couldn't find anything suitable w/o being way overkill in the various salvaged pieces-parts in the barn...
Anyway, thanks for the input even though it was a snipe hunt owing to me thinking only of the part of the puzzle was holding in hand when posted...
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