Clamp meters are now more accurate, compact and rugged

As advances in technology are posing new challenges for testing devices and equipment, manufacturers are coming up with new clamp meters that can meet these requirements

By Richa Chakravarty

Wednesday, January 15, 2014: A clamp meter is a device used for measuring the current in a wire. Unlike a multimeter, a clamp meter does not need to be connected to the circuit in order to read the current. With it, the procedure of breaking the circuit to measure the current can be avoided. The clamp on the device is simply placed around a live wire to measure the current without interrupting the operation of the appliance. A clamp meter uses digital technology to deliver instantaneous readings.

The total clamp meter market in India can be divided into three sub-segments: AC clamps, DC clamps and AC+DC clamps. While AC clamps are the most popular and used for general maintenance, AC+DC clamps are used by customers who need to work on both AC and DC power systems like manufacturers of inverters, batteries, relay control panels, etc. There is a small niche market for leakage measurement clamps primarily used by industrial and process control customers.

Demand for clamp meters

From a basic model used by AC repair centres to models used in complex power parameter measurements, clamp meters are available in a wide range of prices and performance levels. “Presently, the market for clamp meters in India is growing at a healthy rate of approximately 12 per cent, year on year. The market turnover is currently in the range of Rs 400-500 million and is expected to touch around Rs 600-650 million by the end of 2015,” informs Prashant Jain, senior product manager (electrical), Fluke India.

Heavy industries (including cement, steel, glass, textiles, chemicals and fertilisers, etc), industrial manufacturing, process industries and utilities have been the main segments driving the demand for clamp meters. Recently, market players are seeing a good surge in demand from new customer segments like renewable energy, education, defence and power backup. “The major demand for clamp meters comes from the repair and maintenance departments across various industries. Also, these clamp meters play an important role in direct measurements in the electrical industry. Demand is also coming from manufacturers of UPS systems, inverters and batteries,” says Pranay Rana, senior executive, business development, Rishabh Instruments Pvt Ltd.

Types of clamp meters

Clamp meters can be categorised based on their measurement technology—-average sensing clamp meters and true RMS (TRMS) clamp meters. Both have their respective advantages and applications. The TRMS clamp meters, with their advanced circuitry and ability to accurately measure both sinusoidal as well as non-sinusoidal signals, are costlier than average sensing clamp meters. “The TRMS clamp meters find extensive use among industrial users where the current waveform is non-sinusoidal due to high level of harmonics. On the other hand, average sensing clamp meters measure pure sine wave signals and are ideal for technicians working on residential and commercial building repairs and maintenance – where the current has little or no harmonic content,” says Prashant Jain.

The latest in the market

Metravi Instruments is yet to introduced Flexiclamp in Indian market. Also, launched in August 2013, Metraclamp 20 is its latest clamp meter offering high display counts.

Launched in May 2013, Fluke’s new 362 clamp meter is designed to fit easily into the user’s pocket. It can measure AC and DC currents up to 200A. Its AC/DC measurement capability addresses a large user base in the generators, UPS system, inverter and battery manufacturing space.

Representing Mastech, in July 2013, Metro Electronic Products launched MS 2115B and MS 2205 clamp meters.

Adding to its huge portfolio in January 2013, Rishclamp’s 1000A AC-DC clamp meter is the latest offering from Rishabh Instruments. “It is used for the measurement of AC current, DC current, AC voltage and DC voltage. Its features include the measurement of capacitance, ohms, continuity, frequency, duty cycle and temperature,” informs Pranay Rana.

Agilent Technologies has recently added two new series of clamp meters U1210 and U 1190. Both the series have been designed with specific features for different applications

Technological advances

As advances in technology are posing a challenge to testing devices and equipment, manufacturers are now developing instruments that can meet newer requirements.

Compact and portable: Manufacturers are developing clamp meters that are easy to carry, are compact, and yet have numerous features. A compact, low current, AC/DC clamp meter is easy to carry and use—for example, Fluke 362 clamp meter. It delivers high performance and is also rugged. These meters are used in places that generally are out of the reach of other test instruments, especially in areas that are difficult to access like tight cabinets, bundled wires, etc. With features like a detachable display, users can take down the measurement remotely. Also, flexible clamp meters available today wrap around thick cables which were absent in the conventional ones. These latest clamp meters have expandable cable length of 18 inches, hence give enough room to add the cable under test.

High accuracy: The new clamp meters are becoming more accurate. An accuracy of 3 per cent indicates that the actual value of the current could be anywhere between 97 and 103 Amps. Increasing the display counts from standard 1999 counts and 3999 counts to 19,999 counts and 40,000 counts is another evolving trend. Metraclamp 20 recently launched by Metravi offers 40,000 counts. “This feature helps to measure high currents with very low current resolution. While measuring 400A current on a 40,000 counts clamp meter, the current reading can be done up to two places after decimal point. Similarly this feature also helps to measure voltage with high resolution. Hence while doing power analysis, values can be measured with high level of resolutions,” informs Vikram Bhansali, director, Metravi Instruments Pvt Ltd.

The new feature-rich TightSight range clampmeters by Ideal Industries are built to professional quality standards to withstand tough use in commercial and industrial settings. Says Chirag Lodhiya, regional Sales, electrical division, Ideal Industries India Pvt Ltd, “TightSight bottom display and TRMS range of clampmeters by Ideal Industries are built to professional quality standards to withstand tough use in industrial and commercial environment. High frequency rejection (HFR) and EMI shielding features provide accurate voltage/frequency readings on non-sinusoidal wave forms, such as adjustable speed drives.”

TRMS: Today’s clamp meters give the true RMS value of the distorted signal, regardless of how distorted the signal might be. These clamp meters also have built-in low pass filters, which helps in keeping interference from other electronic components away and hence, gives users an accurate reading.

Innovative features: Integration of bluetooth in clamp meters is another important feature introduced by players. Agilent has added new bluetooth capability to its U1210 series. Aslo its U1177A series infrared-to-bluetooth adaptor allows easy monitor measurements and log data up 10-metres range across all android platform devices. This maximises the efficiency and productivity.

Another trend in the clamp meter is the wireless PC interface. Shares Vikram Bhansali, “Other than bluetooth, user can connect the clamp meter to their PC wirelessly and record data. This can be done over a distance of 100m. All this helps a lot on analysing the loads under measurement and their variation with respect to time and in real time.”

Latest clamp meters also offer overload protection that prevents the damage of both meter and the circuit, while protecting the user as well. Also, the autoranging feature automatically selects the proper measurement range rather than the user having to perform manual ranging. A backlight display, easy-to-read characters, and a wide viewing angle make it easier for the user to view the readings in all sorts of conditions. The backlight display automatically sets the correct measurement range, so the user does not need to change or switch positions while taking a measurement.

Safety feature: Today, clamp meters display infrared (IR) temperature readings. Having an IR instrument handy to point and shoot for temperature diagnostics is invaluable. Having it built into the clamp meter truly sets the meter apart. Not only does the clamp ensure that the user can perform all essential electrical diagnostics, the built-in IR makes it easy to identify overheating in electrical panels and other components from a distance without the need for an additional meter.

U1190 handheld clamp meter comes with innovative Vsense which performs non-contact detection of live voltages. “With Vsense, electricians can now perform their tasks more safely by avoiding hot or live voltages. Upon the detection of live voltages, it simultaneously produces a unique combination of two alerts; audible beep alert and blinking LED light, hence increasing safety, shares Mukul Pareek, marketing program manager, Agilent Technologies India Pvt Ltd.

Buying tips

A wide variety of clamp meters are available in the market, and this may confuse buyers while trying to choose the right one. Customers should first check their application’s requirements and assess the electrical load in their system. A rule of thumb is that if you have variable frequency drives installed on motors, power electronics or semiconductors, you should go in for a TRMS clamp meter, which will give accurate readings on all kinds of loads. For residential applications, an average sensing clamp is an acceptable choice and works satisfactorily. Nowadays, clamp meters offer additional functions like voltage, resistance, capacitance measurement as well as other user friendly features like inrush current measurement, backlit LCD displays, min-max, and data hold, which can be valuable to customers.

Some other factors that need to be kept in mind are listed below.

The user requirement: It is necessary to check the requirements of the user, as measurement of DC in amperes can almost double the cost for the user. Also, users should check the specifications of the clamp meter including the jaw size required, accuracy, measuring category (CAT II, CAT III and CAT IV), digital display count and other parameters measured. If a lower ampere is to be measured, then the buyer should select a small-sized clamp, as a bigger variant can be less accurate, suggests Manish Kwatra, managing director, Metro Electronic Products.

Safety checks: Clamp meters should conform to safety standards like IEC 61010 and should be tested at independent test labs like UL and TUV. They should carry the certification markings of IEC, CE, UL and TUV, and customers should ask for relevant certificates. Customers should insist on valid calibration certificates and a genuine manufacturer’s warranty at the time of making the purchase.

Easy to handle: A user should select a clamp meter with easy-to-replace batteries so that the testing is not hampered. An auto-ranging display, which automatically sets the correct measurement range, will eliminate the problem of having to adjust or switch positions while trying to get a measurement while in a tight spot and, hence, save time. Also, one should choose a clamp meter with a large, easy-to-read backlit display that will perform well in real world conditions. Suggests Prashant Jain, “It is always advisable to calculate ‘total cost of ownership’ of an instrument and not just the initial purchase price. It is usually seen that clamp meters with low purchase price proves to be much costly in long run due to low life, frequent repairs and inaccurate readings.”

Agilent’s U1190 Series

• 3000A AC current measurement

• 3000 count large scale LCD display with backlit

• Data hold

• Slide switch to change range

• 10/18inch head cable length

• 7.5mm coil diameter for tight space measurement

• Ergonomically designed one hand operation

• CAT.IV 600V/ CAT. III 1000V safety stand

Agilent U1210 Series

• Large clamp opening of 52 mm or 2”

• High measurement capability of up to 1000 A for AC, DC or AC+DC

• CAT III 1000 V/CAT IV 600 V safety rating

• Includes full-featured DMM with resistance, capacitance, frequency and temperature functions

• High resolution measurements–measure current as low as 0.01 A

• Peak hold capability

• Bluetooth wireless connectivity

Fluke 362 clamp meter

• Designed to fit easily in a pocket

• Special tapered jaw design that makes it extremely suitable for measuring currents in conductors in tight spaces or in bunches

• Small 18mm triangular jaw allows access to tight corners where other clamp meters cannot reach

• Provides the accuracy users can trust

Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine