- Joined
- Nov 13, 2012
- Messages
- 165
A "balanced" 3 phase motor has all 3 phases pulling nearly the same amps. The standard quick and dirty field test is to use an Amprobe successively on each of the 3 motor leads to check the current load per lead. A balanced motor runs smoothly and delivers full rated HP without cooling issues. An unbalance motor heats the heavily loaded windings more than the other(s), and in extreme cases cannot deliver rated HP.
Out in industry, large plants with 3 phase power systems can experience imbalance if there are a lot of connected single phase loads such as resistive heaters or lighting. If a plant system becomes too unbalanced, the motors experience "unbalanced" amp loads. The designers and electricians always try to arrange and connect the single phase loads such that the system, as a whole, remains mostly balanced.
For RPC users, with only 1 or a few motors on an RPC, the unbalance is due the capacitors (or lack of) in the system. Many users run RPCs successfully with little or no balancing. From what I have seen, you only need to have a well balanced system if one or more of the motors routinely run near rated HP, or if you have 3 phase electronics such as CNC drives and the like. With an RPC system, you can use a voltmeter to estimate the balance by comparing the voltage between each of the 3 phases.
Terry S.
edited to correct spelling
Out in industry, large plants with 3 phase power systems can experience imbalance if there are a lot of connected single phase loads such as resistive heaters or lighting. If a plant system becomes too unbalanced, the motors experience "unbalanced" amp loads. The designers and electricians always try to arrange and connect the single phase loads such that the system, as a whole, remains mostly balanced.
For RPC users, with only 1 or a few motors on an RPC, the unbalance is due the capacitors (or lack of) in the system. Many users run RPCs successfully with little or no balancing. From what I have seen, you only need to have a well balanced system if one or more of the motors routinely run near rated HP, or if you have 3 phase electronics such as CNC drives and the like. With an RPC system, you can use a voltmeter to estimate the balance by comparing the voltage between each of the 3 phases.
Terry S.
edited to correct spelling