Motor Frequency Meter with a 4-20 ma output

Do you folks know of any Motor Frequency Meters that have a 4-20 ma output ?
I know a frequency drive would provide that need , but the customer does not want to spend the money at this time. I am looking for something that I can hook up to the motor wires coming off the contactor. If so , what are some of the brand names ?

Thanks so much

if customer unable to spend money this means you provide free item.

where is the variable frequency coming from, if not from a VFD?

DOL or SD system

then 50/60 Hz

Allen-Bradley has some signal conditioner solutions. Here is a part number for frequency in and 4-20mA out. 931S-F1C2D-DC

I have used some of their signal conditioners in the past with good success, have never used one for frequency.

Good Luck

red lion

Rob S. said:

Do you folks know of any Motor Frequency Meters that have a 4-20 ma output ?
I know a frequency drive would provide that need , but the customer does not want to spend the money at this time. I am looking for something that I can hook up to the motor wires coming off the contactor. If so , what are some of the brand names ?

Thanks so much

Click to expand...

May I ask why frequency? It does not change enought to notice in the US.
I use the red loin IFMA freq to analog convertor.
Its range is up to 25KHz if what you are tring to catch is PWM.

They have an old Danfoss drive mounted on a motor. They claim that it does not have a analog output. I imagine that all frequency drives have an analog output, correct ? I am going to go to the customer and look at it in more detail. It is a Danfoss FCM 335.

Thanks

Rob S. said:

They have an old Danfoss drive mounted on a motor. They claim that it does not have a analog output. I imagine that all frequency drives have an analog output, correct ? I am going to go to the customer and look at it in more detail. It is a Danfoss FCM 335.

Thanks

Click to expand...

That drive has one output, on terminal 9, that can be configured as a digital output or an analog output (the ultimate in cheapness of design if you ask me). When configured as an analog output, you can make it into a voltage or current signal, meaning 0-24VDC or 0-20mA, and you can make it proportional to what they refer to as "Feedback". Then in another parameter, you tell it what that "Feedback" signal is. It can be any number of values from within the drive including frequency, or you can have it calculate actual RPM if you like.

The problem is, if they are ALREADY using that singular output as a digital output, like "Running" or "Fault" for example, then you have lost it as an analog output. Chintzy if you ask me...

If that's the case, you would need to find a signal conditioner that can correctly interpret the complex PWM output wave form of the VFD into a value equating to motor frequency. Not an easy task, and I don't know of a transducer that does this, short of using a scope meter with an output, but that would likely cost more than just buying a new better VFD that gives you what you want.

How about a panel meter with Modbus RTU master functionnality?

Someting like that:

http://www.bbinstruments.com/downloads/PD865.pdf

Assuming that Danfoss FCM 335 has Modbus RTU functionnality built in like this specification tell:

http://danfoss.ipapercms.dk/Drives/...actsheets/ProductFactsheets/UK/FCM300/?Page=2

But not every spec show that Modbus is implemented. Hard to tell...

I don't understand why you need to have a frequency meter on an across the line starter
in North America the AC line frequency will be 60Hz with in .5 %
All power systems are connected to the grid any deviation in the line frequency will cause an overload on the system and trip the barkers. even onsite generators run at 60Hz to keep the motors and other equipment running at the correct speeds. if you running a VFD then the speed output can be set to either VFD output frequency or motor speed. they may be different by a only a few Hz but it much.