Substation battery ground monitoring

[trat1208]

The plant I work at has recently had some issues with battery grounds (equipment misops, false indications, etc). We are fairly effective at locating and removing them but usually we don't notice them until a problem has occurred. Aside from increasing operator surveillance of battery grounds, does anyone know of a good way of monitoring battery ground strength?

All of our battery systems are 125Vdc, floating with respect to ground. The chargers have the ground detectors where you push the positive or negative button and positive or negative ground voltage is displayed.

Other engineers I have talked to about this problem have installed systems where they have intentionally grounded positive and negative through similar high resistances and wired Vdc meters with 4-20ma outputs across these resistors, making a center-point high resistance grounded battery. They then hook up the analog outputs to the DCS and set it to alarm when either voltage dips below a certain level and they can also trend the pos-gnd and neg-gnd voltage analogs against operating conditions at their plants.

This seems like a pretty good system, but I'm surprised there is not a product out there that can do this all in one package and based on ground resistance. Are there any monitoring products available out there that can give a real time measurement of positive and negative to ground battery resistance and produce analog outputs of these values for connection to a DCS. Any suggestions or experiences?

 

[bacon4life]

Our newer battery charges have continuous monitoring for gounds built in already that we monitor via SCADA contacts.

Some protection relays such as a 487B also include battery voltage and ground alarms.

Are you sure you want an analog signal or would an alarm be good enough?

 

[slavag]

Hi Trat1208
I would recommend to you Bender system

http://www.bender-de.com/wocms.php?siteID=121&lngID=2

Those devices are include 4-20mA signal->on line resistance monitor.
It's work in lot of power plants and substations.
Very intresting point, curve isn't linear, you need add to DCS, SCADA HMI some formula for present Ohm value. Take it in account in future
Best Regards
Slava

 

[slavag]

Sorry, forgot.
Please check.

http://startco.ca/

 

[ScottyUK]

Areva's MR621 '623 '625 and '627 are worth a look. I haven't used all the models but the MR625 behaved very well on a fairly large 110V DC system.

http://www.areva-td.com/solutions/US_366_Solution+Index.html

and search a bit.


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If we learn from our mistakes I'm getting a great education!

 

[submonkey]

Hi,

Perhaps connect the midpoint of the battery to earth via an auxiliary relay. If either positive or negative terminal comes into contact with earth, the relay will energise and trigger an alarm.

I appreciate that this isn't an analog indication, but it certainly does the job.

 

[apowerengr]

Primax of Canada makes a battery charger with the monitoring and SCADA outputs you're looking for.

 

[ScottyUK]

Replacing the charger just to get monitoring seems a pretty expensive way of doing it... do you work for the government?


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If we learn from our mistakes I'm getting a great education!

 

[DiscoP]

The BA300 from Areva has been around for a few years. It indicates faults on either the +ve or -ve leg, as well as under/over voltage and high source impedance.

http://www.areva-td.com/solutions/US_404_BA300+Battery+Monitoring+and+Alarm.html

 

[jpflying]

The Areva BA300 which DiscoP recommneds is a good unit. We have several of them installed and they work fine. Depending on the type of fault detected therelay operates one of two voltage free contacts which are called urgent or non-urgent.