Inexpensive current & frequency transducer?

[SteveH]

Anyone found an inexpensive frequency/current transducers? This is to hook into my Autostart PLC so I can monitor the MEP remotely while it's running.

There's various frequency transducers on ebay, but they're large, and not inexpensive (also outputs don't really match the 4-20ma or 0-10v I'm looking for). It kind of hurts to pay anything more than $20 when that's the price of the Hardy Frequency/Voltage meter (and there's several apparent clones that do current/voltage/frequency for the same price). I'm even considering buying one of these to see if it can be modified...

Thanks in advance
Steve

 

[PeterD]

This search on eBay turned up a few in the $50 to $100 range for frequency transducers. For voltage, http://www.ebay.com/sch/i.html?_odk...TR0.TRC0&_nkw=voltage+transducer&_sacat=12576 returns items as well, and they are less expensive.

 

[ARYankee]

Have you tried Automation Direct?

 

[SteveH]

Re: Inexpensive current & frequency transducer?

This search on eBay turned up a few in the $50 to $100 range for frequency transducers. For voltage, http://www.ebay.com/sch/i.html?_odk...TR0.TRC0&_nkw=voltage+transducer&_sacat=12576 returns items as well, and they are less expensive.

Yes.... Those are the prices I'm seeing. That's going to come to around $150 to $250 to get all three parameters into the PLC. Seems high when I can get a LCD meter and current loop to do nearly the same thing for $20

 

[SteveH]

Re: Inexpensive current & frequency transducer?

Have you tried Automation Direct?

No... I'll take a look this evening. Thanks!

 

[PeterD]

Yes.... Those are the prices I'm seeing. That's going to come to around $150 to $250 to get all three parameters into the PLC. Seems high when I can get a LCD meter and current loop to do nearly the same thing for $20

If you are willing to 'roll your own' then why not just build them? The voltage is a simple A-D converter. For frequency, a tachometer circuit would work just fine. I could do both for perhaps $20 in parts... And, who knows, maybe you can adapt a HF $4.95 DVOM to do what you want easily!

 

[bmwsyc]

What are you looking for in current sensors? I may be able to help out.

 

[SteveH]

What are you looking for in current sensors? I may be able to help out.

Looking for a pair of transducers to mount below the lugs in the distribution box, one to measure each leg (so at least 0-50A, preferably a little higher). These will interface to the PLC, with either a 4-20ma or 1-10v signal (I've got both options).

I did get a Paladin frequency transducer last night on ebay - $100 (ouch!), and as PeterD says, voltage isn't too difficult.

Realistically, this is all 'nice to have' (as I haven't yet worked out a way to control frequency), but I thought it would be good to monitor and alarm (email/txt) if there's any issues during the monthly test run

-Steve

 

[PeterD]

There are already current transformers and a monitoring circuit (the meter mostly) already in the MEP. Consider the potential of tapping off that existing circuit to feed your PLC.

 

[SteveH]

There are already current transformers and a monitoring circuit (the meter mostly) already in the MEP. Consider the potential of tapping off that existing circuit to feed your PLC.

Yes - I'm also looking at that (trying to find out what the currents through the various meters represent), though that still doesn't give me the 'split' across the two 110v legs.

Thanks
Steve