The application and the asset under test will determine whether low or high power is required. Here are three examples:
- Contamination – The application of high power will result in the test piece heating. Many tests are performed on bonds, connections, and contacts in low-current applications. If you have contamination between surfaces, a higher test current and power will ‘blast’ through the contamination resulting in a good test result, even though the connection will be unreliable in use. Testing with low current and power will reveal the problem much more readily.
- Rough surfaces – An example where high power is an advantage is testing connections or bonds with rough surfaces. In some such cases, you will obtain a good test result with a low test current and power, with the contact points between contact surfaces being low enough resistance. However, applying a higher test current and power will heat these small points of contact. The result is a changing test result as the heating takes place, highlighting the problem.
- Frayed wires – On lower current carrying systems (typically less than 10 A), testing with higher power will cause heating on weaknesses such as frayed wired, with the remaining wires presenting a higher resistance.
The 25 W power output can be supplied continuously for at least 60 seconds, meaning you can measure resistance with inductance. However, the DLRO10HD/HDX is unsuitable for testing large inductive circuits, such as power transformers.