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Voltage Measurement in Noisy Environment

Voltage Measurement in Noisy Environment

Voltage Measurement in Noisy Environment

(OP)
Hi, I am working on a large storage battery where I need to measure the voltage of individual batteries.
Associated with the storage is a large bi-directional inverter which is extremely noisy (RFI)
I need to measure individual battery Voltages around 100 Volts. Past experience tells me that electrical noise will be a big issue so I would really like to couple the transducers to the PLC via fiber optics.
So far I have only found one supplier whose transducers require a separate fiber to Voltage output module these extra steps seem to me to be over-complication.
I imagine some sort of network like the RS-485 Master Slave arrangement often seen in switchgear only fiber of course.

Has anyone seen anything like that?

Thanks
Roy

RE: Voltage Measurement in Noisy Environment

Hi Roy,
Have you looked at Linear's battery monitoring chip? It's specifically for individual battery monitoring in series strings. They seem to have thought of everything.

LTC6802-1
or
LTC6803-3

They may have more too.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Voltage Measurement in Noisy Environment

(OP)
Keith,
I just looked at the two devices you mentioned unfortunately the Voltage rating is too low, we need to measure batteries in series not individual cells, the LTC68 series has a maximum Voltage rating of 60 Volts

I made another post under Electrical / Electronic Engineering other topics
Thanks for responding
Regards
Roy

RE: Voltage Measurement in Noisy Environment

roydm
There are wonderful lowcost passive devices which can be used as voltage dividers. Wouldn't they work?

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Voltage Measurement in Noisy Environment

Hi Roy,

This just feels wrong to me. Seems like way to much hassle.

I think if I were faced with the same issue I'd:

1) Try to reduce the EMI being spewed into the battery stack. Include perhaps some capacitors to shunt the noise from the inverter. Possibly a choke too?

2) Find a digital meter that has 485 output that allows you to poll it.

3) Get a handful of 485 isolated adapters.

4) Network your meters thru the isolated 485 adapters.

5) Hook your PLC as a MASTER to the now isolated 485 network.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Voltage Measurement in Noisy Environment

(OP)
Gentlemen.
Thankyou for all the good ideas.

IRstuff;
We don't have it built yet, Im just trying to avoid the problem we experienced last time
The vendor described his inverter as "A radio station in a box"

Skogsgura,
I'm not sure how I could use those, everything we purchase will have to be approved.

Itsmoked,
This is pretty much the conclusion I have come to
1) I will ask the engineer to get tough on the vendor
2) I have located some likely looking transducers
3) Good idea
4) I was hoping I could isolate the transducers from the PLC via fiber optics rather than running copper from a noisy environment to the PLC, I haven't given up on that yet.
5) Yes, that's what I was hoping to do, avoid having to convert the measurement twice.

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