Single Phase Bridgeport
Single Phase Bridgeport
(OP)
I am a hobby machinist and have a Series 1 Bridgeport.Yesterday, I toasted my rotary phase converter. Before I spend $500 on a new one, I'd like to look at the possibility of replacing the Bridgeport three phase motors with single phase 220v motors.Has anybody done this?





RE: Single Phase Bridgeport
I was going to purchase a surplus Bridgeport from our company but couldn't get the 3 Phase power needed. I'm only 800' away from a power company source.
You might post your question in the "Electric Motors & Controls Engineering Forum" for answer.
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
That is essentially the reason I didn't go that route, cost.
They made no mention of only one service as my shop is on a separate service from the house. My electrical engineering buddies at work talked about the cheaper operation on 3-Phase though I'm thinking a 17% surcharge would mitigate any savings.
I think I had better see if I can find out how the drive for the Bridgeport was converted.
Does Bridgeport make a single phase drive?
RE: Single Phase Bridgeport
Have you considered building your own rotary phase converter?
IIRC, consists primarily of a fractional hp motor and a 3ph motor as large as the largest in your shop.
Griffy
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
good luck
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
Bridgeports and similar run just fine on simple static phase convertors. I have over 8 years on one convertor with no problems. I couldn't begin to guess how many reversals I made while tapping holes.
Rotary convertors come into their own when dealing with higher inertia, harder starting loads such as lathes with significant chucks and such.
Some high end rotary convertors have banks of capacitors that fire through a contactor for extremely high torque requirements. Expect the contacts to require replacement on a regular basis. Keep a spare set in the shop.
Also, keep a suitable fire extinguisher handy and make sure the location of the convertor will not prevent access to it's disconnect in the event of a fire. Those capacitors really stink when they burn....
RE: Single Phase Bridgeport
Are you using a pull rope to start rotation on the idler as your normal starter method? If so, get an old dryer or washing machine motor to spin the idler. Much more reliable.
Griffy
Laziness is the mother of invention!
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
The only proviso is that the motor should be wound with "inverter grade" wire, otherwise motor service life may be reduced. I wound up having to rewind a 30 yr old motor after 18 months time on the inverter. Not sure if it was the inverter or simply motor age that finally killed the motor.
What will a single phase motor do for you that's better than what the inverter provides?
RE: Single Phase Bridgeport
I have done it both ways, i.e. static and rotary. I toasted one static after years of service and have been using another static for years with no problems. The static phase converter (rated for starting 5-7.5hp)starts a 5hp lathe which serves as an idler and all the other 3 Phase machines are wired in parallel via a separate circuit breaker box.
Kapitan's ebay suggestion sounds very reasonable but you can likely get by even cheaper if you can invest the time by reworking your rotary: get a used 1/2hp single phase motor and mechanically link it to your 3 Phase idler motor via a v-belt. Wire a momentary switch to the single phase motor. Wire L1 & L2 single phase input to your 3 phase idler via a circuit breaker switch. Leave your 220V single phase input switch to the 3 phase idler motor OFF while you momentarily start the single phase motor which in turn will spin the 3 phase motor. Once the 3 phase is spinning at 60% syncrhonous speed (you can hear it ramp-up), switch ON the 220V L1, L2 input to the 3 phase idler which will now run on single phase but will act like a generator and put out three phase power. L3 obviously only exists downstream of your idler. This is not as simple as your capacitor fix but I believe it is more robust and safer.
Jesus is THE life,
Leonard
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport
http://www.fadalcnc.com/Phase_Converters.htm
http://www.cncpros.net/phaseperfect.pdf
RE: Single Phase Bridgeport
RE: Single Phase Bridgeport