Porschefix
Hot Rolled
- Joined
- Dec 3, 2009
- Location
- Bluff Dale
I have a friend that has a 1950's vintage Oliver 270 direct drive saw. It has a 5HP 220V motor, swings a 14" blade and used to cut through 2" oak as fast as he could push it through when it was new to him about 20 yrs. ago. He has moved his shop a couple of times since then, now the saw is powered by a 10hp rotary converter. He says the saw now will not cut 2" oak without bogging down losing power. He is a master door maker and he knows what all his machines are capable of when they are working right. All other equipment in the shop works fine. Apparently the power has declined over time gradually and he has become concerned, and asked for my help.
Rotary converter output is 256V 256V 265V . About a 10V drop each leg under heavy load @10ft. of 10gauge wire to box and only .4 volt differential in each supply leg between converter and motor. I checked the current under load, pulls about 22A at startup and spins up easy. Motor 6.4 ohms between all fields. Motor has no bearing axial or endplay and turns freely. No unusual vibrations and fence is aligned with blade, saw has a feeder that has been slowed down to allow for loss of power, blade is sharp. I cannot find any mechanical problems, can a 3ph motor become less powerful just by getting older? I have not heard of such a thing but I cannot find anything wrong. Any suggestions of what could be wrong or what else to check?
Rotary converter output is 256V 256V 265V . About a 10V drop each leg under heavy load @10ft. of 10gauge wire to box and only .4 volt differential in each supply leg between converter and motor. I checked the current under load, pulls about 22A at startup and spins up easy. Motor 6.4 ohms between all fields. Motor has no bearing axial or endplay and turns freely. No unusual vibrations and fence is aligned with blade, saw has a feeder that has been slowed down to allow for loss of power, blade is sharp. I cannot find any mechanical problems, can a 3ph motor become less powerful just by getting older? I have not heard of such a thing but I cannot find anything wrong. Any suggestions of what could be wrong or what else to check?
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