need to use vfd for two machines

Dear All,

I have power 60 Hz 380 V Ac but my two machines are designed on 50 Hz 380 V.

How can i use a inverter for both machines.

Please help me asap

Thanks in Advance

You can use a VFD for each MOTOR, but it's not a good idea to use one VFD to run an entire machine, let alone two machines. VFDs are not designed to have motors start DOL down stream of them, it damages the power components inside. They are designed to control the motor directly, and also, just motors. If you have other loads on the machine that need 380V at 60Hz, the VFD is not a good option for those. it would work, but depending on the devices, may cause them harm or vice versa.

What you may need to do is a thorough investigation of the entire electrical circuits and look carefully at the needs of each individual component, then make decisions one by one.

Many machines designed for 50 hz will run on 60 hz. As lraef said, the motors will run 20% faster. Directly driven loads may be running too fast so a VFD may be needed to slow to original design speed. If the loads for the motors are belt or chain connected to the load, change the ratio of the pulleys or sprockets.

I was hesitant to weigh in. I figured you could simply slow the motor down using the VFD. After all, that's what they do...

While it is possible to design a full-machine power supply for a machine (or 2) based around a VFD as the source, it's not a simple task, and should only be attempted if you either know what you are doing, or are prepared for the damage caused by doing it wrong

Sizing and filtering are very important considerations.

rootboy said:

I was hesitant to weigh in. I figured you could simply slow the motor down using the VFD. After all, that's what they do...

Click to expand...

I completely agree, using a VFD on the motor is by far the best way. I was just offering some alternative info.

Gene Bond said:

While it is possible to design a full-machine power supply for a machine (or 2) based around a VFD as the source, it's not a simple task, and should only be attempted if you either know what you are doing, or are prepared for the damage caused by doing it wrong

Sizing and filtering are very important considerations.

Click to expand...

Right, but the filtering is NOT built in to a VFD because the motor doesn't need it, that's why I don't recommend it as an overall power source. Most people cannot adequately design a filter that will avoid over heating transformers, power supplies and other SMPS type devices frequently found in machines now.

As to the comment about 50Hz motors running ok on 60Hz, that's true in most cases, but not this one. Motors need for the power source to be close to the same ratio of voltage and frequency they were originally designed for. So in the case of a motor designed for 380V 50 Hz, that's 380/50= 7.6V/Hz. If you feed it with 480V 60Hz, that's still 8.0 V/Hz, close enough that the motor can tolerate it. However, in THIS case he has 380V 60Hz, which is uncommon in the world. That means his motors will get only 6.3V/Hz, about 17% too low. That means the peak torque output will be about 70% of normal, then at the same time the speed will increase 20%. The combination will mean an early demise for the motors.

Your post says you live in Faisalabad in Pakistan which is in the centre of Pakistan

Pakistans supply grid standard is 230/400 volts 50 Hz

You would need to be running your machine on an isolated generator
probably of American origin for a 60 Hz supply

Gil47 said:

Your post says you live in Faisalabad in Pakistan which is in the centre of Pakistan

Pakistans supply grid standard is 230/400 volts 50 Hz

You would need to be running your machine on an isolated generator
probably of American origin for a 60 Hz supply

Click to expand...

He might be working in one of the 5 or 6 countries in the world who use 380V 60Hz power. Mostly small island nations. Rare, but they do exist. I've often wondered how that happens, for some small country to adopt an electrical standard that means they cannot buy standard off the shelf equipment from anywhere.

You can use a VFD when the machines do not have one very big motor.
Find yourself a motor just freerunning, on the same 380 Volts. or higher like 400.
the VFD should be a simple one without internal feedback etc. just a simple frequency converter.
The motor will take care of the problems when starting.
For what items do you need the conversion as most modern machines can cope with 60 Hz, like power suplys etc. only the motors will run too fast, and coils can not have this higher freq.

Your description does not provide enough information to answer your question. A "machine" could be almost anything.
How many motors on each "machine"?
Do the motors run continuously?
Are there other electrical loads?
What is the current requirement?

U need to indentitified and separate 3 phase load and 1 phase load,

example,
www.szpowerdrive.com/products/frequency-converter.htm

http://www.engineering.com/Electron...wer-Supply-Frequency-Between-50-and-60Hz.aspx

Good info here; applies primarily to individual motor applications but is educational in the Voltage/Frequency Ratio and resulting consequences.