from 60Hz to 50Hz territory 1

[PaulLag]

Hello Everybody
Hope you are fine and safe

Please, I apologize for the most experts, but it has passed a long time since I dealt with electricity lessons as well I am not an expert so that I kindly ask for your help.

I have red this thread, too

https://www.eng-tips.com/viewthread.cfm?qid=335720

But allow me to write you my question and my concerns


I have recently being offered to buy a refrigeration system (meaning compressor,fans, controllers, some other low voltage electrical stuff) working @60Hz in US voltage (meaning 115V-220V-460V) to move it in a 400/3/50 230/1/50 territory

My first thought is that this system won’t work as in US tension, then I thought that at least it would be necessary to examine all the electrical characteristics of the system, as nameplates data of all the compressor and other equipment, examining if it can work at different voltages.

My concerns refer to the passage to a frequency that is lower than the original (I assume that all components in low voltage should have problems, the high ones should run slow) and to the fact that the system won’t be designed for the new Voltage frequency combination.
In the best case, changing the tension, it would give a lower performance but I fear in the long time It would damaged.

Again, these assumptions are based on long time concepts, they may be wrong.

The reason I am writing in the forum is to kindly ask for an help, concerning some practical hints to mind concerning this kind of topic, or if anybody has ever experienced similar requests.
It would be of a great help if somebody could kindly recommend me some practical literature that would help me to increase my knowledge about the topic


I'd like to thank you all in advance, stay safe

 

[xnuke]

See faq237-1224.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[waross]

You must not exceed the Volts-per-Hertz ratio when changing frequency.
460 Volts at 60 Hz is a ratio of 7.67 Volts-per-Hertz.
That translates to a Voltage of 383.
But all is not lost.
460 Volt rated motors are universally used on 480 Volt systems. Volts at 50 Hertz.
The Volts per Hertz of a 480 Volt system are 8 Volts per Hertz.
That converts to a 400 Volt system at 50 Hz.
That takes care of all components connected across the line.
Other components will have to be evaluated individually.
All Most induction motors will run 5/6 slower.
Fan motors may be an exception to the 5:6 ratio.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[itsmoked]

I'd council you don't do this with refrigeration equipment which is the most demanding and generally optimized type systems. Systems that push the hardware right to the limit for long hours on the hottest days.

Not the type equipment to try to run at the wrong frequency and different speeds. Rarely ever works out. Not the deal you might think it is.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[LittleInch]

And if any of the components are running centrifugal type compressors then your pressure generated reduces by 70%.

The one that will bite you is find all of the 110V switches and systems which would sit at 230V.

You would need to provide 110V to the unit unless the 110V came from a transformer tap.

so feed the beast with 60htz supply or forget it.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[FacEngrPE]

Most smaller refrigeration compressors are positive displacement machines centrifugal units start at 100 to 200 hp.

Positive displacement compressors operate at constant torque. As most are cooled by the returning hot refrigerant, running slower makes them hotter. At the lower flows the expansion valve might not work as expected. Surely the refrigeration capacity will be reduced.

It would be a better idea for this equipment to obtain an inverter frequency converter that can be fed 50 Hz and output 60Hz. An off the shelf inverter drive might work, but you should consult with the factory as the application might need unusual settings.

Fred

 

[PaulLag]

Dear All

At first please let me thank you all for your prompt, polite and expert answers.
I truly appreciate your help.
I really think they helped to clarify me several aspects of the topic, that at the end seems to be a forced utilization of an equipment in an environment it has not developed for.
I’d have a kind further request, if possible.
Please, would it be possible to recap the situation with some governing equations or formulas I could refer in similar cases ?
This would help to have a quick method to refer in case of similar topics for a first analysis, and to understand how all variables affect the output.


Thanks again

 

[itsmoked]

Sorry Paul but we no-can-do with a single exception.

The lone exception is that for a motor to be happy you need to keep the Volt-Hertz number that the motor was designed for the same or you'll likely have trouble.

A Motor that is name-plated 460V 60Hz has a Volt-Hertz design of 460/60 = 7.7
Don't run it at some other V/Hz point unless you know exactly what's going on and by that I mean knowledge of the type of load, duty cycle, starting frequencies, inertial aspects, etc., etc.

Because motors are fairly tough and a little flexible an EE with some knowledge can make predictions about whether or not one might be able to violate or push the V/Hz limit a bit in specific applications. There is no equation or fixed rules we can give you.

In this case we can tell you "don't screw with any of this in regards to modern refrigeration equipment" or you will be replacing everything piece-meal and at great expense while possibly losing a lot of product or production at the same time.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[PaulLag]

@ MR Itsmoked
OK, I understand. Many thanks

@ All
I would like to thank you all for your kind and precious help.

Please, if you don't mind, could you recommend me a good book where I could study on and improve my knowledge on this topic?
Thanks in advance