Non-bridge device for large motor winding resistance readings
Non-bridge device for large motor winding resistance readings
(OP)
Historically we have used bridges for winding resistance readings.
Our metrology people tell me these are no longer available, and we are having problems finding parts to maintain the ones we have... so they want to find a new device for winding resistance readings.
I am looking at two options:
1 –DLRO such as Megger DLRO 10 shown here
http ://www.meg ger.com/us /products/ ProductDet ails.php?I D=77&D escription=
2 – Transformer "Ohmmeter" such as Megger MTO210 shown here:
http: //www.megg er.com/us/ products/P roductDeta ils.php?ID =183&D escription=
Both look to have accuracy which is more than sufficient. (I'm thinking we need something like 0.5% or 0.5 milliohms, whichever is smaller when reading windings in the range 50 – 500 milliohms.)
The DLRO is preferable since we already have them on-site for other purposes. The question is how long will it take the device to stabilize when reading an inductive load. Megger says the DLRO has an "inductance" model which makes them stabilize faster, but they can't say exactly how fast. Also I'm not sure how long battery lasts when using this feature. We would use the Kelvin clip probes instead of the spring-loaded prong probes.
The Transformer Ohmmeter seems better suited to the application, but I'm not sure it is required to buy this additional equipment if the DLRO will work.
Any comments or suggestions? Have you had luck using equipment other than bridge for winding resistance tests? Or found bridges that are still readily available ?
Our metrology people tell me these are no longer available, and we are having problems finding parts to maintain the ones we have... so they want to find a new device for winding resistance readings.
I am looking at two options:
1 –DLRO such as Megger DLRO 10 shown here
http
2 – Transformer "Ohmmeter" such as Megger MTO210 shown here:
http:
Both look to have accuracy which is more than sufficient. (I'm thinking we need something like 0.5% or 0.5 milliohms, whichever is smaller when reading windings in the range 50 – 500 milliohms.)
The DLRO is preferable since we already have them on-site for other purposes. The question is how long will it take the device to stabilize when reading an inductive load. Megger says the DLRO has an "inductance" model which makes them stabilize faster, but they can't say exactly how fast. Also I'm not sure how long battery lasts when using this feature. We would use the Kelvin clip probes instead of the spring-loaded prong probes.
The Transformer Ohmmeter seems better suited to the application, but I'm not sure it is required to buy this additional equipment if the DLRO will work.
Any comments or suggestions? Have you had luck using equipment other than bridge for winding resistance tests? Or found bridges that are still readily available ?
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(2B)+(2B)' ?





RE: Non-bridge device for large motor winding resistance readings
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If we learn from our mistakes I'm getting a great education!
RE: Non-bridge device for large motor winding resistance readings
Any other experience or comments on the general question of what works well for this test?
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(2B)+(2B)' ?
RE: Non-bridge device for large motor winding resistance readings
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: Non-bridge device for large motor winding resistance readings
MEGGER DLRO10 and DLRO10X
Digital Low Resistance Ohmmeters
• Accurate results in under three seconds
Bill
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"Why not the best?"
Jimmy Carter
RE: Non-bridge device for large motor winding resistance readings
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(2B)+(2B)' ?
RE: Non-bridge device for large motor winding resistance readings
RE: Non-bridge device for large motor winding resistance readings
As has been pointed out by other members, beware of damaging the instrument when disconnecting leads because of inductive kick - refer to Manual regarding the order of disconnecting test leads.
I Seem to remember that potential leads should always disconnected
first before disconnecting current leads. Please refer to Ducter Instruction manual!
RE: Non-bridge device for large motor winding resistance readings