What is a Clamp Meter?
Clamp Meters are electrical instruments which have two jaws which open and can be clamped around an electrical conductor. In this way it is easy to perform live current measurements without having to shut down an electrical installation.
True RMS Clamp Meters
Nowadays there are many types of clamp meters. There are True RMS clamps which are perhaps more expensive but they can measure AC current more accurately. There are clamps with flexible jaws which are very useful in cases where there is not enough space for a traditional clamp meter. And, of course, modern clamp meters are not solely able to measure current.
Always consult the clamp meter's manual in order to determine the maximum conductor size which the meter is capable of measuring. Also, the manual shall mention if the clamp meter is suitable for measuring insulated or bare wires.
- Make sure that the jaws of the instrument are completely closed, firmly touching one the other. If there is an open space between the jaws, the measurement might not be correct.
- When measuring DC current, the Clamp meter usually has an offset at zero current. This offset must be zeroed (DC current clamps have a zero button) before beginning the measurement. Since DC current clamps are sensitive of the earth's magnetic field, it is important not to change the clamps orientation after zeroing.
- It is important to keep the jaws clean and in good condition.
- As with any other measuring instrument, it is important to have the clamp meter calibrated according to manufacturer's specifications, in order to ensure that it operates within its limits.
Clamp Meter Applications
Clamp meters are used in many applications. In residential appliances, it is often necessary to measure the loads of individual branch circuits or to ensure that a circuit breaker operates correctly. In commercial and industrial environment, the three phase circuits should be checked. Each phase should have more or less the same current. In all appliances it is critical to measure leakage currents.