What is Contact Resistance?
Contact resistance is the resistance to current flow when the contacts touch each other (when the device is in the off state) due to surface conditions and other reasons.
Where Does Contact Resistance Occur?
- Other Switching Devices
What Problems Does the Contact Resistance Test Detect?
It is used to measure resistance in different applications of electrical testing. Consisting of a DC ammeter and several other components, this tester detects the following issues;
- Loose connections
- Sufficient tension on bolted connections
- Worn contact surfaces
- Dirty or worn contacts
Why is Contact Resistance Test Necessary?
The contacts on the circuit breaker need to be checked periodically to ensure that the breaker is healthy and functional. Poorly maintained or damaged contacts can cause sparks, loss of phase or even fire. Measuring contact resistance helps identify corrosive corrosion of contacts and allows diagnosis and prevention of contact corrosion. An increase in contact resistance can cause a high voltage drop in the system and this needs to be controlled.
What is done during the contact resistance test?
Two common checks performed on the contacts of a circuit breaker are visual inspection check and contact resistance check.
Visual inspection check includes inspecting the contacts of the circuit breaker for any signs of pitting due to arcing and worn or deformed contacts.
The second check is the contact resistance measurement. This involves injecting a constant current, usually around 100A, through the contacts and measuring the voltage drop across it. This test is done with a special contact resistance measuring device. Then the tester calculates the resistance value. The resistance value read on the device should be compared with the value given by the manufacturer. The value should also be compared with previous records.
Both of these tests need to be done together. Because the contacts have good contact resistance and can also be damaged. Therefore, to be considered reliable, a contact must have good contact resistance and pass a visual inspection test.
MT-DCRT; It is a portable contact transition resistance meter designed for measuring circuit breakers, switching equipment, busbars and any low resistance using 50A or 100A DC test current according to IEC 61010-1 and IEC 61326-1 standards. It has current measurement feature and display. It performs contact resistance measurement operations with high accuracy.
- 50 or 100 DC Test Current
- 3.5″ Touchscreen Color HMI Display
- 4-Lead Measurement Method
- Included Printer
- Accuracy ±(0.01%)
- PC data exchange via USB connection
- PC Application
- Internal memory to save 400 test results
- Industrial Rugged Case
0 – 2,50mΩ
0 – 5,0mΩ
|Power Supply||230VAC, 50Hz ± 10%,Single Fase|
|Output Current||50A or 100A|
|Test Time||6 second|
|Power Supply Protection Fuse||4A|
|220 VAC Input Protection Fuse||5A|
|Operating Temperature||0°C – 45°C|
|Storage Temperature||0°C – 55°C|
|Humidity||< 90% RH|
|Display||3.5″ Touchscreen Color HMI Screen|
|Memory||Internal Memory for 256kB-400 Tests|
|Printer||58mm Thermal Printer|
|Dimension ( W x H x D)(mm)||430x230x370|