A clamp meter is essentially an electrical meter equipped with an AC current clamp. Also, called tong tester or clamp-on ammeter, a clamp meter combines a current sensor with a digital multimeter. The meter is used to measure circuit current without requiring any de-energising or disconnecting. A clamp meter predominantly has a plastic body, with ferrite iron-consisting hard jaws underneath that are designed to note, concentrate, and assess the magnetic field generated courtesy current as it moves via a conductor.
First created to serve a single purpose, the clamp has evolved over the years to serve multiple functions. The modern clamp meter provides more measurement functions, specialised measurement features, and greater accuracy. The clamp meters on the market today come with most the functions synonymous with a digital multimeter – for instance, the ability to compute voltage, resistance, and continuity.
A clamp meter is usually preferred to measure high current levels. DMMs can’t measure 10 A current for 30 seconds or more at a stretch without posing any damage risk to the meter. The minimum current range offered by a clamp meter is 0 A to 100 A. Several models come with a range extending up to 600 A. Then there are quite a few other models that stretch up to 999 or 1400 A. Some plug-in accessories could measure up to 2500 A.
The clamp meter’s popularity or widespread usage could be credited to two basic things: safety and convenience.
- Safety: A clamp meter lets an electrician ring road the age-old cutting method wherein a meter’s test is inserted, leading into the circuit and taking an in-line measurement of current. A clamp meter’s jaws don’t have to meet a conductor when measuring things.
- Convenience: When measuring, it isn’t required to shut off the current-carrying circuit, resulting in a major efficiency boost.
A clamp meter is used on industrial controls, industrial equipment, industrial/commercial HVAC, and industrial/commercial/residential electrical systems. The usage is primarily for:
- Service: Repairing current systems as and when needed.
- Installation: Troubleshooting installation issues, supervising apprentice electricians when they are performing equipment installation, and performing final circuit tests.
- Maintenance: Performing preventative and scheduled maintenance, and system troubleshooting.
Using Clamping Meters
An electrician with a solid grounding in test equipment usage fundamentals would be much more capable of using a modern testing and troubleshooting equipment such as a clamp meter.
Large AC Currents
The clamp meters’ ability to measure huge AC currents is dependent on a straightforward transformer action. When the instrument’s jaws or current probe encircling an AC current-carrying conductor is clamped, the current gets coupled via the jaws, much like a power transformer’s iron core, and within another winding linked across the meter input’s shunt. Smaller current gets delivered to the input of the meter, thanks to the proportion of primary and secondary windings wrapping the core. Generally, the primary winding is denoted by a conductor that has the flexible current probe or jaws clamped around it.
Current is among a clamp meter’s basic measurements. Modern clamp meters can measure both DC and AC current. Usual current measurements are done on many of the electrical distribution system’s branch circuits. Ascertaining the amount of current flowing in different branch circuits is a routine task for most electricians. To measure current, select Amps DC or Amps AC; open the clamp meter’s jaws; and close them surrounding a conductor.
Modern clamp meters can measure both DC and AC voltage. Usually, AC voltage is made courtesy a generator and later distributed via an electrical distribution setup. For isolating and fixing electrical issues, taking voltage measurements is important. Testing battery voltage is another usage scenario. For circuit troubleshooting, the first thing that gets measured is proper voltage supply.
Resistance measurements are documented as “ohms”. Resistance values could differ significantly, from some milliohms to several billion ohms for insulators. Most clamp meters can measure as low as 0.1 ohms. When the resistance measured is more than the meter’s upper limit, “OL” shows up in the display of the meter.
Continuity is essentially a no-go/quick go resistance exam differentiating a closed and open circuit. Clamp meters equipped with a continuity beeper lets you complete several continuity tests quickly and easily. The beep sound goes off when detecting a closed circuit, not requiring viewing the meter during testing.