CATU MT5805 Micro-Ohmmeter
The CATU MT5805 is a portable micro-ohmmeter used by electrical engineers, electrical contractors, and substation maintenance teams in Ireland to measure very low resistance values on switchgear contacts, busbar joints, earthing connections, and high-current paths. Powerpoint Engineering supplies the MT5805 alongside our wider electrical test equipment range, with calibration support, accessory supply, and operator training to back it up.
A general-purpose multimeter cannot measure micro-ohms accurately. Lead resistance and contact film alone are higher than the resistance you are trying to measure. A dedicated micro-ohmmeter delivers a stable, controlled DC test current and uses a four-wire Kelvin measurement to remove lead resistance from the result. The MT5805 is the right tool for that work.
What the MT5805 measures
- Contact resistance on circuit breakers: detect contact wear and erosion before it becomes a thermal problem.
- Busbar joints and bolted connections: verify joints are tight, clean, and within manufacturer specification.
- Earthing and bonding paths: confirm high-current earthing connections are doing their job.
- Cable joints and terminations: trend resistance values over time as part of a condition-based maintenance programme.
- Welded and bolted connections on busbars and earthing systems where loose or oxidised connections show up as higher resistance.
Key features
- 4-wire Kelvin measurement: separate current and sense leads remove lead resistance from the result, the only way to measure micro-ohms accurately.
- Stable DC test current: delivered at the appropriate level for the measurement range, giving repeatable results across return visits.
- Microhm-level resolution: sufficient resolution to trend small changes in contact resistance over time.
- Portable, site-ready build: sized for substation, switchroom, and field use.
- Backlit digital display: clear reading in poor light common to substation environments.
- Result storage: on-board memory or notebook recording for inclusion in maintenance records.
Why micro-ohm measurement matters
The point of low-resistance testing is not the absolute value, it is the trend. A reading taken today, compared with the commissioning baseline and the last maintenance reading, tells you whether a connection is healthy, drifting, or about to cause a real problem. A few microhms of drift on a circuit breaker contact can be the early warning of overheating that, if left, becomes a thermal event under fault current. The MT5805 gives you the accuracy to make that trending meaningful.
Specifications: what to confirm before you order
|
Specification |
What to confirm |
|
Test current |
DC test current sufficient for the connection types you measure |
|
Resistance range |
Microhm-level resolution at the bottom end, milliohm and ohm at the top |
|
Measurement method |
4-wire Kelvin with separate current and sense leads |
|
Test leads |
Length and termination matched to the connections being measured |
|
Power |
Battery and mains options for substation and field use |
|
Calibration |
Supplied calibrated; periodic recalibration through Powerpoint's lab |
Target users and applications
- Electrical engineers commissioning new switchgear and verifying contact resistance against factory data
- Electrical contractors carrying out planned preventative maintenance on industrial switchgear
- Utility maintenance teams running periodic substation maintenance and outage testing
- Renewable site operators testing interconnection switchgear, collector busbars, and BESS connections
- Industrial maintenance teams running condition-based maintenance on critical electrical assets
Typical applications include circuit breaker contact resistance measurement, busbar joint verification, switchgear commissioning, fault-finding after a thermal event, and benchmarking new equipment against its factory test sheet. For higher-current testing requirements, the Megger MJOLNER 600 micro-ohmmeter may be the right step up; for the routine connection resistance work that dominates everyday substation maintenance, the MT5805 is well-matched to the task.
Powerpoint Engineering supplies the CATU MT5805 alongside our wider calibration and repair services for portable test instruments.
FAQs
Why can a multimeter not measure micro-ohms accurately?
A multimeter measures resistance using a small test current, often less than a milliamp. At that current, lead resistance, contact film, and noise are larger than the resistance being measured, and the reading is dominated by error rather than the actual connection. A micro-ohmmeter delivers a higher test current and uses 4-wire Kelvin measurement to give a meaningful result.
What is 4-wire Kelvin measurement?
Kelvin measurement uses two pairs of leads: one pair carries the test current to and from the device under test, the other pair senses the voltage drop across only the device. By separating current and sense paths, lead resistance is excluded from the measurement, which is what makes micro-ohm readings accurate.
Does the MT5805 need calibration?
Yes. As a precision measurement instrument, the MT5805 should be recalibrated periodically to remain trusted on contract and reporting work. Powerpoint Engineering's calibration laboratory recalibrates micro-ohmmeters and supplies a traceable certificate.
To match the right CATU MT5805 configuration to your switchgear, busbar, and earthing measurement work, request a quote or speak to our team for compatibility advice.
