Voltage Too High

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I called the Edison service planner today, told him of the high voltage readings.

He says that 500v is too high and to call a trouble man to asses the situation.

Ended up running other calls and did not get back to check the motor voltage.

Gave up on the repair of the pump panel.

Strange, a man that worked for me several years ago and had a heart attack. By the paperwork I signed I assumed he went on permanent disability.

Ends up he is second in command at the water company and told his boss to call me.

I will post again when the POCO gets done with the testing.

Thanks for the help and entertainment!
 
steve66 said:
A motor will actually pull slightly less current with a slightly higher voltage.

The watts remain the same, and is basically determined by the power it takes to move whatever you are pumping.
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I have found this to be a myth.
When I worked in a chem plant I had to install an em genset so that they could still sell product even if they lost power and couldnt produce more they wanted to still sell everything on hand.
The generator had a dial on it to vary voltage output. I had heard the same thing but when I increased the voltage the current increased.
When I decreased the voltage the current decreased. Eventually you may get to the point of diminishing return where the motor will not have enough voltage to move the load and then the amps go way up.
But run of the mill 3 phase motor volts up amps up.
 
quogueelectric said:
I have found this to be a myth.
When I worked in a chem plant I had to install an em genset so that they could still sell product even if they lost power and couldnt produce more they wanted to still sell everything on hand.
The generator had a dial on it to vary voltage output. I had heard the same thing but when I increased the voltage the current increased.
When I decreased the voltage the current decreased. Eventually you may get to the point of diminishing return where the motor will not have enough voltage to move the load and then the amps go way up.
But run of the mill 3 phase motor volts up amps up.
Click to expand...
The Baldor tech reference document, a collection of papers by Ed Cowern, agrees with you, and explains it.

EFFECTS OF HIGH VOLTAGE
One of the basic things that people assume is, since low voltage increases the amperage draw on motors, then by the same reasoning, high voltage would tend to reduce the amperage draw and heating of the motor. This is not the case. High voltage on a motor tends to push the magnetic portion of the motor into saturation. This causes the motor to draw excessive current in an effort to magnetize the iron beyond the point to which it can easily be magnetized. This generally means that the motors will tolerate a certain change in voltage above the design voltage but extremes above the designed voltage will cause the amperage to go up with a corresponding increase in heating and a shortening of motor life. For example, older motors were rated at 220/440 and had a tolerance band of plus/minus 10%. Thus, the voltage range that they can tolerate on the high voltage connections would be 396 to 484. Even though this is the so-called tolerance band, the best performance would occur at the rated voltage. The extreme ends, either high or low, would be putting unnecessary stress on the motor.

He also has a graph that puts all into perspective.
 
quogueelectric said:
I have found this to be a myth.
When I worked in a chem plant I had to install an em genset so that they could still sell product even if they lost power and couldnt produce more they wanted to still sell everything on hand.
The generator had a dial on it to vary voltage output. I had heard the same thing but when I increased the voltage the current increased.
When I decreased the voltage the current decreased. Eventually you may get to the point of diminishing return where the motor will not have enough voltage to move the load and then the amps go way up.
But run of the mill 3 phase motor volts up amps up.
Click to expand...

Thank you, this is the hands on experience I was looking for. I told the customer this but had nothing but theory to back it up.
 
GeorgeB said:
The Baldor tech reference document, a collection of papers by Ed Cowern, agrees with you, and explains it.

EFFECTS OF HIGH VOLTAGE
One of the basic things that people assume is, since low voltage increases the amperage draw on motors, then by the same reasoning, high voltage would tend to reduce the amperage draw and heating of the motor. This is not the case. High voltage on a motor tends to push the magnetic portion of the motor into saturation. This causes the motor to draw excessive current in an effort to magnetize the iron beyond the point to which it can easily be magnetized. This generally means that the motors will tolerate a certain change in voltage above the design voltage but extremes above the designed voltage will cause the amperage to go up with a corresponding increase in heating and a shortening of motor life. For example, older motors were rated at 220/440 and had a tolerance band of plus/minus 10%. Thus, the voltage range that they can tolerate on the high voltage connections would be 396 to 484. Even though this is the so-called tolerance band, the best performance would occur at the rated voltage. The extreme ends, either high or low, would be putting unnecessary stress on the motor.

Great info, I am going to us this Monday. This account has a lot of potential. Thanks.
Click to expand...
 
quogueelectric said:
I have found this to be a myth.
When I worked in a chem plant I had to install an em genset so that they could still sell product even if they lost power and couldnt produce more they wanted to still sell everything on hand.
The generator had a dial on it to vary voltage output. I had heard the same thing but when I increased the voltage the current increased.
When I decreased the voltage the current decreased. Eventually you may get to the point of diminishing return where the motor will not have enough voltage to move the load and then the amps go way up.
But run of the mill 3 phase motor volts up amps up.
Click to expand...
The relationship between current and voltage depends on a number of factors.
If you have linear passive loads the current will increase with voltage.
For motors it gets a bit more complex.
If the motor is lightly loaded then reducing the voltage will reduce the current. It's a feature incorporated on many VFDs.
But, if the motor is running close to, or at, full rated power output, reducing the voltage increases the current in most cases.
 
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