Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
I imagine it would spin a bit faster, perhaps putting extra wear-and-tear on the motor's parts. It will probably work for a while, but chances are it will also break a little sooner than it normally would.
Most synchronous AC motors will run as well on 50 or 60 Hz. Things work out a little like this:
Speed in RPM = 120 * (applied frequency in Hz / number of magnetic poles)
So for example a typical 2 pole synchronous AC motor running at 50 Hz. will rotate at 3,000 RPM and that same motor running on 60 Hz will rotate at 3,600 RPM.
50 Hz / 2 poles = 25 and 120 * 25 = 3000
60 Hz / 2 poles = 30 and 120 * 30 = 3600
That is based on no load conditions for the motor, just freely spinning.
The same holds true for a synchronous AC generator. Small single phase AC home generators that are 2 pole deliver 60 Hz running at 3600 RPM and 50 Hz running at 3000 RPM.
One thing that has not been mentioned yet is if you try and run a motor on the wrong frequency it may overheat.
I have seen this with the small "C" frame 50hz motors running on 60hz.
One thing that has not been mentioned yet is if you try and run a motor on the wrong frequency it may overheat.
I have seen this with the small "C" frame 50hz motors running on 60hz.
Yeah, good point. That is why I said "Most" in my post. Works both ways too. While living in Italy I had a huge American (US) refrigerator running off a transformer (240 to 120). While the compressor was not thrilled with 50 Hz. it did run the 3 years I lived there.
A synchronous AC motor will obviously run best at the frequency it was designed to run at. Running above or below that frequency will generally result in the motor running slightly warmer than it was designed to run at. The question becomes how forgiving is the motor which varies from motor to motor. The voltage is another story, similar but another story. Running a motor designed for 208 VAC on 240 VAC will obviously cause it to run hotter than it was designed for. Possibly 208 to 220 not that much but at 240 VAC you really start pushing the curve or your luck. Within reasonable limits the motor will not run any faster or slower based on applied voltage, it will run hotter at the elevated voltage. If you have a variac that will handle the load then it should run fine.
actually I get a better shave in the US than the UK because my electric razor runs at a faster frequency. I need to make sure I change the voltage though, which is your only worry...
simon, only because the original components were de-rated sufficiently to allow for people doing this kind of thing. Such engineering is common in consumer devices. Use the wrong device at the wrong frequency either way and it can be very bad.
simon, only because the original components were de-rated sufficiently to allow for people doing this kind of thing. Such engineering is common in consumer devices. Use the wrong device at the wrong frequency either way and it can be very bad.
Absolutely agree. While off topic I will share this. As mentioned while in Italy the refrigerator ran just fine all 3 years and was then sold to another American. However, that was not true of all US made 60 Hz appliances (for want of a better word). My then wife dragged along a "toy" that was designed for 120 VAC and 60 Hz. To this day I remember the loud pop, a small flame and the plume of smoke when it failed doing its thing. Really scary as it was inches from my head when it did it. Hell, my hair could have caught fire. So heed the warning of Sceadwian as this is the voice of experience talking.
Heating wise, a 200VAC motor at 50Hz will run at the same temperture as a 240VAC motor at 60Hz unless it has been pushed beyond its field weakening region.
I think you're fine.
Very few of the 50/60Hz motors I deal with hit their field weakening region before about 70 Hz.
If you have any means to measure temperature, the threshold can be worked out if you're into that sort of masochism.
At work we push 3 phase motors to the limit. If the tag says full load is 15.5 amps at 480 volts I use an amp clamp to set the heaters to trip out at 16 amps. Then we put the machine under load and adjust the load so the amp clamp reads 15.9 amps. The motors get hot enough to cook and egg running like that none stop. The motors run for many years like that. Roller bearings will go bad before the motor burns up. Bearings are a quick cheap repair compaired to the price of a new or rebuilt motor.
YES that is right......1979 to 1985 I worked in a company where they tried to get 40 HP out of 20 HP motors. We had 6 machines all the motors would burn up in 3 to 4 weeks. Management complained about high maintenance cost. I tried to explain you can not expect a 20 HP motor to produce double its rated HP for very long but they insisted we must have higher production rate to make a good profit maintenance cost are eating up all the profit. I told them how to fix the problem but they insisted they were right and I was not. The plant manager was barely keeping the company a float, he realize there was no future there so he quit. The new plant managed was a the comptroller promoted to plant manager he knew nothing at all about maintenance or being plant manager. One day the bearing went out in a machine the new plant manager refused to let me buy new bearing claiming we had reached our budget limit for the month so he told me to weld the old bearing back together. I told him it was not possible to weld bearing back together. He told me to do it or look of another job. So I welded the bearings together and put the machine back together. Production started the motor the main drive shaft was locked up because the welded bearings would not turn. The plant manager was so made he fired me, he actually did me a favor. About 1 year later the company went out of business.
With the proliferation of variable frequency drives (VFDs), modern induction motors are usually designed to run at various frequencies. However, voltage compensation is required as frequency changes. In the simplest mode, voltage changes in exact proportion to the frequency. In some industrial applications, we have run motors, with nominal nameplate ratings of 60Hz, all the way up to 90Hz with no problems. Operation at lower frequencies is generally a bigger problem. Firstly, the voltage must be reduced in proportion to the frequency. Secondly, motors with a fan operated off of the main motor shaft will suffer from much slower air circulation, and this is often the limiting factor. For very low speed operation, a different means of cooling may be required.
The 60 Hertz system is actually more efficient than the 50 Hertz system
240 Volts 50 Hz UK motor should ideally be fed from a 277 Volts 60 Hertz supply.
Lower voltage causes less torque. It depends how heavy the starting torque of the machine is.
The motor would run at 240 Volts 60 Hertz ok as long the motor is not loaded to its maximum capacity.
Heating wise, a 200VAC motor at 50Hz will run at the same temperture as a 240VAC motor at 60Hz unless it has been pushed beyond its field weakening region.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
