The market that was previously served adequately by basic clamp meters is evolving rapidly and getting a lot more sophisticated. Power quality analysis tools are keeping pace with the changes by offering many new features
By Belal Khan
Although clamp meters, along with voltmeters, have been the traditional tools for electricians when investigating a building’s electrical supply, the vast changes in how that supply is used, calls for much more sophistication in today’s power analysis tools.
Computer rooms and data centres, for instance, require a consistent and clean supply to ensure the stability of their networks.
Changing trends
In order to ensure that a building’s power supply is up to expectations, it is often necessary to monitor it over an extended period of time, rather than just doing simple spot measurements.
“With the latest generation of power quality analysers, it is possible to monitor the supply to a building for any desired length of time—from a few hours to a number of weeks. By doing this, it is possible to get a full picture of both the electricity demand and the quality of the supply,” says Shailendra Kalra, MD, Livingston India.
Power quality analysis allows the facilities managers to obtain a better understanding of the demand cycle of the building, identifying the peak periods, if any. This information allows them to identify the causes for these peaks and look for ways to balance their power usage over the period. It also helps to ensure that the phases feeding the building are balanced and that the entire load is not unevenly weighted on a single phase.
Such analysis identifies any issues there might be in the supply, due to such factors as harmonics and spikes, which could be problematic for some types of equipment. It also identifies any drops or increases in the supply, plus the obvious total power losses. Where emergency standby generators are being deployed, it shows the switchover time being achieved, and helps users decide what type and rating of UPS system they may require.
“At Livingston, we work with leading manufacturers of such equipment—Chauvin Arnoux, Fluke and Dranetz. Through these relationships, we are able to offer our customers high performance test solutions for more accurate analysis,” adds Kalra.
Making the buying decision
Buying a clamp meter not only requires looking at the specifications, but also at features, functions and the overall value represented by a meter’s design.
Today’s clamp meters have most of the basic functions of a digital multimeter (DMM), but with the added feature of a current transformer built into the product.
In terms of safety, clamp meters should be tested at independent test labs like UL and TUV. Safety is the one parameter which should not be compromised on. Users should remember that buying cheaper, low quality products in the market may prove to be much more expensive in the long run. Safety starts with choosing the right meter that adheres to accepted safety standards for the environment in which the instrument will be used.
Created primarily as a single-purpose test tool for electricians, today’s models incorporate more measurement functions, higher accuracy, and in some instruments, very special measurement features.
Categories
Clamp meters can generally be categorised based on their measurement technology—the typical sensing clamp meters and true RMS (TRMS) clamp meters. Both have their respective advantages and applications.
Indian companies have come out with new products such as power loggers, clamp meters with power capabilities and other application-specific clamp meters for the domestic market.
Today’s major T&M players focus on some of the critical market requirements and hence offer several innovative features in their products. Let’s take a look at the latest clamp meters available in the market, and their functions and features.
The first one in the line is the ‘detachable display’. Wireless technology allows the display to be viewed up to 9.14m away from the point of measurement, without affecting measurement accuracy. Fluke’s 381 series remote display TRMS AC/DC clamp meter offers a detachable, remote display for easier, faster and safer measurements. It offers up to 1000A AC and DC measurements, 1000V AC and DC voltage measurements and includes the iFlex flexible current probe that expands the measurement range to 2500A AC while providing increased display flexibility, the ability to measure awkward sized conductors, and improved wire access.
Latest products in the market
Model: 27 Auto – 400A AC by MECO
- AC current of 2A, 20A, 200A and 400A (auto-ranging)
- AC voltage of 2V, 20V, 200V and 600V (auto-ranging)
- DC voltage of 200mV, 2V, 20V, 200V and 600V
- Resistance: 200, 2K, 20K, 200K, 2M, 20M (auto-ranging)
- Special functions: Data hold, audible continuity, diode test, APO jaw opening of 25mm (max.)
Model: AC Digital Clamp Meter by Kyoritsu
- Fully safe jaw
- Ergonomic over-moulded body offers convenient one-hand operation
- Large easy-to-read display with 0.01A resolution
- Accurate reading with True RMS
- 60/600/1000A auto-ranging
- Long battery life
- Adheres to the following safety standards: IEC 61010-1 CAT IV 300V / CAT III 600V
Model: RISH Clamp Power 1000A/400A AC/DC by Risabh Instruments
Measures the following parameters:
- AC and DC voltage up to 1000V
- AC and DC current up to 1000A/400A
- Inrush/peak value measurement
- Active, reactive and apparent power
- Horse power measurement
- Measures up to 49th harmonics
- LPF mode for VFD application
- Rotating clamp jaws facilitate measurement at physically awkward positions such as vertical bus bars and conductors placed at positions difficult to access.
- Clamp jaws can be opened or closed with the trigger placed at the bottom side, away from the jaws. This allows users to place their hand at a safer distance from the live conductor. This greatly reduces their exposure to electrical shocks.
Large jaw opening:
Jaw opening of 51mm and 41mm for standard wire diameter of 50mm and 40mm for 1000A and 400A, respectively.
Inrush current measurement:
The clamp meter will be triggered by an inrush current of >5A. Inrush current for 100msec is measured.
Data hold function:
By pressing the ‘Data hold’ button, readings on the display can be launched for hands-free operation.
Min-max function:
By pressing the ‘Min/Max’ button, the clamp meter will start recording the latest minimum and maximum readings.
Backlighting:
The clamp meter can be used in poor light conditions with the help of its bright white backlight.
Non-contact voltage detection:
The meter can detect the presence of AC voltage between 100V to 1000V 50Hz/60Hz without any electrical connection and give acoustic signals as an indication.
Three-phase power measurement:
The clamp meter can measure power in 3-phase 3-wire or 3-phase 4-wire (symmetric as well as asymmetric) networks without any of the manual calculations required when using some other clamp meters.
LPF mode:
This is available for voltage and current for true measurement of VFD application.
TRMS measurement:
In order to calculate the true value of distorted waveforms due to the presence of the high crest factor or harmonics, TRMS measurements are done for AC voltage and current.
Auto power off:
To save on battery usage, the clamp meter will automatically shut off if it detects no activity for 10 minutes.
Continuous ‘ON’ mode:
In this mode, ‘Auto power off’ is disabled.
Battery indication: ‘Low battery’ indication along with double moulded cover for soft-touch handling and a firm grip of the instrument.
