# I have Problem with Hertz and RPM



## catguy (Dec 1, 2017)

Hi gents,
I'm New guy here I need from you to discuss Hertz and RPM issue.

I have problem with Genset 1.5 MVA 1500 rpm 50 Hz and 400v 

The Hertz are 44 Hz or less the voltage 360v or less around 335v the RPM 1500 but when I go to increase the hertz from 44 Hz to 50 HZ the voltage go to 400v,
but the problem With RPM it run to 1778 RPM,
Why when I increase the Hz to 50 The RPM go to 1778 ? 

Can somebody help me with this issue.
thanks for help


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## motormonkey (Jul 10, 2016)

What's the genset make and model?
What does the data plate say about voltage, amps or watts, Hertz, rpm, etc.?
How are you measuring Hertz, RPM, voltage?
How are you adjusting Hertz, RPM, voltage?

It sounds like 1778 RPM may be the correct speed.


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## catguy (Dec 1, 2017)

Thanks for reply
The generator was cat3512 the alternator burn up because short circuit of two phases,I have done replace the alternator by Japanese made with same rated nameplate of 3512
Japanese made nameplate : 
Avr of that was model : MX 321- 50/60 1500/1800

Excitation values : 
380/5.0/STD 
full load 56v/3.2A 
No load 10v/0.6A

But I'm using CDVR and I did not use the AVR MX 321


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## catguy (Dec 1, 2017)

How are you measuring Hertz, RPM, voltage?
How are you adjusting Hertz, RPM, voltage?

EMCP2 and fluke


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## motormonkey (Jul 10, 2016)

It appears that there are many different types of Cat3512 generators. Different voltages, different frequencies, different power ratings. A wild guess would be that you have the incorrect alternator and/or AVR in it. I know nothing about Caterpillar generators though. Sorry, but I can't help you. Maybe someone else can help.


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## KRE (Nov 29, 2011)

catguy said:


> Hi gents,
> I'm New guy here I need from you to discuss Hertz and RPM issue.
> 
> I have problem with Genset 1.5 MVA 1500 rpm 50 Hz and 400v
> ...


Set the engine speed to 1500rpm an it will be 50 hertz, your set may be rated at 400 but std is 220/380 for a 50 hertz machine. sounds like your voltage regulator is adjusted wrong, so set the hertz first then set the voltage regulator next an every thing should be OK. 
What country are you in?


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## catguy (Dec 1, 2017)

The generator already at starting 1500 RPM but 44 Hz, by adjusting the hertz from EMCP2 Hz potentiometer it go to 50Hz and 400 v,the problem is RPM jump to 1778.

I took the CDVR and tested on another Genset was fine also the ECM generator was good both of them was good and fine.

Here is my problem the RPM direct proportion to HZ 
1500 RPM @44HZ


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## KRE (Nov 29, 2011)

catguy said:


> The generator already at starting 1500 RPM but 44 Hz, by adjusting the hertz from EMCP2 Hz potentiometer it go to 50Hz and 400 v,the problem is RPM jump to 1778.
> 
> I took the CDVR and tested on another Genset was fine also the ECM generator was good both of them was good and fine.
> 
> ...


You have a miss adjusted EMCP II as that control panel is nothing more than a large PLC with a LCD screen. You will have to dis-guard the panel reading an get the engine at 1500 RPM then program the EMCP II to read 50 hertz, this is done with the flywheel tooth count. If you know the tooth count program it in. Once the engine speed is correct you will have to adjust the MX 321 voltage pot to get the target voltage you want. With the MX 321 being there I'm guessing you have a StamFord Newage alternator which is a good unit. All you problems can be corrected in less than 5 minutes by a good gen-tech. I'd suggest if you don't know what your doing at this point hire someone who does it will be cheaper that destroying the gen-set. 
Does this unit have a Woodward 2301A, load share an speed control device or is it a stand alone black start unit only?


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## catguy (Dec 1, 2017)

Hi,

I found the ECM speed reading totally different comparing to the EMCP2 ... the correct reading is ECM.
Is there any one can help by discussing this matter?

EMCP 2 from MPU sensor but, How the ECM get Speed reading ?
Thanks


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## KRE (Nov 29, 2011)

The EMC your referring to is this an old control panel, or is the 3512 your working on, an newer electronic engine?
You can drill an tap the flywheel housing an install a mag pick up, then program the flywheel tooth count into the EMCP II, that is done all the time. Once the EMCP II is reading RPM/Hertz correctly, you can tie in the remote from the MX321 to the EMCP II and control the Voltage, Under-freq roll off and such from the panel very easily. The EMCP II an III are very versatile panels an will do what ever you require, as it is nothing more than a multi parameter PLC w/a LCD read out. The default code for the II is 13231, unless someone has entered another pass word, if that is the case an you don't have it, it will cost to get it reset. No one I know will release the back door codes to none Cat trained personal.


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