Ideal Clamp Meters Description
Ideal Clamp Meters
A Clamp Meter combines a current clamp with the basic functions of a digital multimeter. Clamp the "jaw" around a conductor to measure current. Over the years current clamp meters have evolved to also include a host of additional features.
How to buy/choose an Ideal clamp meter:
- Choose a clamp meter that gives accurate and repeatable results.
Make sure your clamp meter reports the True-RMS reading. Otherwise noise from everything from a variable frequency drive to compact fluorescent bulbs can result in a less accurate reading. The majority of Ideal Clamp Meters on sale at Tequipment.net feature True-RMS measurment. You should always make sure that the clamp meter meets the industry accuracy standard: 2% ± 5 counts. Beware of accuracies stated to ± 10 counts, as these meters can have twice the error when measuring low currents.
- Do not compromise on safety
Make sure the clamp meter has the correct safety rating (CAT I, II, III, etc.). Ideal Clamp Meters are rated either CAT III or IV. You should also check that the meter's design will allow you to use it easily while wearing Personal Protective Equipment (PPE).
- Make sure the clamp meter works where you do
Check the specifications for the amperage and voltage range you will be working on. Also consider the ambient temperature range if you will be working in a hot environment. Is it rated only for indoor use only? Be sure the clamp meter display you select has large, easy to read characters. Some displays may seem adequate when viewed in a showroom but then fail to perform in the workplace. Real world conditions mean a wide viewing angle and backlight are a must - luckily Ideal Clamp Meters feature large displays with bright backlighting so you can easily read the display in work environments.
How does a clamp meter work?
Clamp meters and adaptors measure this field using one of two technologies. For DC currents, "Hall Effect" is used, while for AC currents "Inductive" technology is used. Hall effect and induction are noncontact technologies based on the principle that for a given current flow, a proportional magnetic field is produced around the current-carrying conductor. Both technologies measure this magnetic field, but with different sensing methods.
Hall Effect Technology
The Hall effect sensor consists of three basic components: the core, the Hall effect device, and signal conditioning circuitry. The current conductor passes through a magnetically permeable core that concentrates the conductor's magnetic field. The Hall effect device is carefully mounted in a small slit in the core, at a right angle to the concentrated magnetic field. A constant current in one plane excites it. When the energized Hall device is exposed to a magnetic field from the core, it produces a potential difference (voltage) that can be measured and amplified.
The ability of clamp meters to measure large ac currents is based on simple transformer action. AC current constantly changes potential from positive to negative and back again, generally at the rate of 50 Hz or 60 Hz. The expanding and collapsing magnetic field induces current in the windings. This is the principle that governs all transformers. When you clamp the instrument’s “jaws” around a conductor carrying ac current, that current is coupled through the jaws, similar to the iron core of a power transformer, and into a secondary winding which is connected across the shunt of the meter’s input. A much smaller current is delivered to the meter’s input due to the ratio of the number of secondary windings vs. the number of primary windings wrapped around the core.
Usually, the primary is represented by the one conductor around which the jaws are clamped. If the secondary has 1000 windings, then the secondary current is 1/1000 the current flowing in the primary, or in this case the conductor being measured. Thus, 1 amp of current in the conductor being measured would produce 0.001 amps or 1 milliamp of current at the input of the meter. With this technique, much larger currents can be easily measured by increasing the number of turns in the secondary.
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