Circuit Breaker lugs temperature monitoring
Circuit Breaker lugs temperature monitoring
(OP)
Trying to find a suitable way of monitoring the lug temperatures of a ~1000V circuit breaker. I see that infrared pyrometers are quite common but that simply won't work in this case. I'd like direct contact rather than monitoring the air temperature near the lugs however the obvious problem is isolation from high voltage & current. However medium voltage generators and motors monitor winding temperatures with RTDs so I thought this would be a possibility. I see one manufacturer's data sheet for a thin film RTD for slot insertion and it's dielectric strengh is shown as 3200V. Has anyone tried this method of monitoring, say on bus bars? Any suggestions are greatly appreciated.






RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
I haven't used the method your talking about but here's a site that might give you some more info:-
http
desertfox
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
Keith Cress
kcress - http://www.flaminsystems.com
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
Infra-View: max. ambient ~50C without cooling
Bridex: 0 - 65C
I don't want to add a jacket to the sensing head - there's no cooling water or air (compressed or fan-driven) supply available.
RE: Circuit Breaker lugs temperature monitoring
There several firms that make them -one is below.
http:
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
http://ww
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: Circuit Breaker lugs temperature monitoring
A better solution than infrared, is a fiber-optic temperature sensor for electrical equipment utilizing fiber-optic technology to provide temperature data 24 hours a day, 365 days a year. The fiber is connected via a mounting fixture on bus bars, splices, circuit breaker finger stabs, etc. Attached from an electronics module (mounted in a safe area) directly to your PLC via serial Modbus, you will know exactly when thermal escalation begins.
Perfomance Stats:
Temperature Range: -20°C to +120°C (-4°F to 226°F)
Resolution: 1°C
Accuracy +/- 2°C
more info? email me at OBR@powellind.com
RE: Circuit Breaker lugs temperature monitoring
Those standard NTCs are accurate within a few degrees if you don't care to calibrate them individually and a lot better if you do.
Did a check between 23 and 159 C a few weeks ago and that works quite well. My test set up was with a 10 kohms series resistor at 25 C, so 25 C is in the middle of the measuring range. That means that you could easily go down to -20 C and lower.
One thing: the impedance is around 10 kohms or lower. That means that capacitive pick up could be a problem. But easily overcome if you put a low pass filter on the input of the receiver. Use a time constant around 10 seconds to get very good 50/60 Hz suppression.
Do you need to record temperatures or do you need to sound an alarm or similar?
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Circuit Breaker lugs temperature monitoring
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Circuit Breaker lugs temperature monitoring
I've used these thermostatic devices successfully for protecting high voltage motor windings from overheating due to impact loading.
They were fixed with epoxy resin to the coil windings close to the exit from the stator slots.
You could strap them to each switch busbar & if required, provide additional insulation resistance with class H glass type material (sleeving) at mating surfaces.
You would have to specify the upper temperature limit required
with your order. Their accuracy/repeatability is excellent.
RE: Circuit Breaker lugs temperature monitoring
RE: Circuit Breaker lugs temperature monitoring
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: Circuit Breaker lugs temperature monitoring
We had a model specific issue with a temperature controller. We found a possible replacement but the replacement was for indoor use and the application was outdoors in Ontario, Canada. The price was low so we purchased a replacement on speculation and did some testing. We found that as the ambient temperature dropped below the rated minimum temperature, found that the instrument error was equal to the temperature difference between the actual temperature and the minimum rated temperature. We decided that if the unit was overheating when the ambient was that cold that it may be an advantage to get an alarm signal at a little less than the normal set point. We put the replacement in service and never had an issue.
The point is:
When a device is used below the minimum rated temperature what happens? If the only effect is a shift in calibration, is the shift acceptable in the proposed application?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Circuit Breaker lugs temperature monitoring