60Hz motor at 50Hz

[CaseyK]

Don:

Between post #1 and #3, please another thread asking how many poles were on a 1200rpm 60hz motor, I am gonna say he has a 60hz motor.

Probably just cheaper just to get a new motor, unless it is a biggie.

regards.....casey

 

[corkers]

Bob

400/230V is, I believe, European and is supposed to happen in Ozz. Do not believe it. They would have to replace a lot of trannies and reset the tapping switch on a lot of others. Have not got the money to upgrade subs now let alone go into that nonsense.

Correct me if im wrong but to affect this change wouldn't the supply companies only have to wind down the generated voltage at the (relatively) few power stations in the supply grid...

As everything is relative the ~ 4% change would filter through. I know its a wank but when in Oz do what the europeans do (thank God it's not the Yanks for once...LOL)

 

[BobB]

Correct me if im wrong but to affect this change wouldn't the supply companies only have to wind down the generated voltage at the (relatively) few power stations in the supply grid...

To a degree yes. However, when equipment is designed to do a job these days, under/over voltage generally causes overheating, loss of power etc.

I remember when I first started my apprenticeship, the first part of the workshop I frequented was the motor rewind shop. The motors were huge by today's standards. Massive shafts, lots of room in slots, easy to wind. I rememeber winding 5 t0 10 HP motors in 3 to 4 hours by hand.

Then the Siemens, Schach etc motors arrived from Europe. NO FAT in the design. They had small slots, lots of kWatts of power for their size, small diameter rotors (no room to put your hand in). In fact, most of them were wound by machine. Got to a point that a 5 HP motor took 2 days to wind. Cheaper to buy a new one.

The biggest problem was that a 5 HP old motor would quite happily run at 15% overload and never fail. Overload one of thes "slim" design new babies by 5% and watch it self destruct. A lot of companies found out the hard way. It was like winding a 200 or 400 hZ job. They were very long and narrow in the slots (mining drills etc).

Quite frankly, there are a lot of trannies out ther that would have trouble being tapped down that far. Dropping the voltage from the power stations would also mean that all the generator systems would have to be altered.

Worse still, a lot of UPS units are designed to work within a few (relatively speaking) volts of 415. A lot of them would have to be modified/replaced also. Can you imagine the cost?

I am now an "old phfaardt" (relatively speaking). I do not believe it will happen in my time.

 

[rsdoran]

The original question was:

Guys,
I have a 460V 60Hz drive and would like to operate it in Australia at 415v and 50Hz. Is this OK? what problems should I consider?

Simple answer, YES.
If supplying a 415v 50HZ motor...none. All motor values can be obtained.
A 460v 60 HZ motor you would have to derate the motor.

I am not sure about some of the issues mentioned. I have to agree with Thomas that most motors can handle a 10% or more over/under voltage.

You can use a 460vac 60HZ VFD and motor as long as you match HP/torque requirements at 415vac 50HZ.
HP = (torque x rpm)/5250 Torque= (HP x 5250)/rpm
A 4 Pole motor at 50HZ will run 1500 rpm

I am not as qualified as most here but this is how I see it.

 

[DonsDaMan]

The problem with line voltages is that the more distant the regulator, the more variation you're going to get. You can get line losses by voltage drops on lines, as well as voltage blooming by sudden drops in current demand.

For example, if the source were regulated at 400 Volts, and the amount of current flowing through the line caused a 5% voltage drop due to line losses, the end user would see 380V. However, the users nearer the regulator will still see 400V, due to less line length.

Now, the current draw is high to get so much drop. Company A, with a 5000A pull closes down for the night, so the current demand suddenly drops by 5000A... The alternator is putting out VA, and since the regulator hasn't yet seen the voltage change, the A's become V's, and the voltage can rise to 440 or more (or less), for a few tens of milliseconds, depending on line impedance.

There are a lot of considerations over just raising taps to regulate large networks.

I don't know if it's been answered, but the 1200 RPM motor is a 6 Pole, so would run at 1000 RPM with 50 Hz excitation. (divide 7200 by synchronous speed to get poles for 60 Hz. Divide 6000 by synchronous speed to get poles for 50 Hz).

Ron,

SteveD's original topic was "60Hz motor at 50Hz," hence my question... drive, motor, or both?