FEATURE TEST & MEASUREMENT
NEED HELP CHOOSING THE RIGHT CLAMP METER?
With so many different technologies and clamp meter models available, choosing the right product for the job can be a minefield - whether it’s for low current AC, DC for photovoltaic and battery systems, or peak load measurement to troubleshoot breakers tripping. Here, Martindale Electric explains the different types of products available to reliably measure current during the installation and maintenance of equipment
T
here are five main types of current clamp meters available:
CURRENT FORK ELECTRICAL TESTERS These have a small fixed jaw and are suitable for where access is limited for basic measurement. Most measure just AC current, but some, such as the ET4 and ET5 from Martindale, measure both.
CLOSED JAW POCKET SIZED CLAMP The closed jaw provides higher accuracy and improved resolution of lower currents. Typically, auto-ranging, with multiple current ranges from 30A through to 600A, and resolution to 0.01A, this type of clamp meter can be specified for AC current only or AC/DC current.
HIGH CURRENT LARGE JAW, CAT IV SAFETY RATED CLAMPS Suitable for application on bus bars in industrial and utility facilities, the CAT IV
CPA SERIES FOR AC AND DC CURRENT MONITORING
Carlo Gavazzi has launched the CPA Series of power analsyers for AC single phase and DC monitoring. A contactless hall effect sensor allows current measurement AC 50-300A and DC 50-400A. The CPA Series provides a flexible solution for
monitoring of both AC and DC power using the same device, the contactless technology ensures a fast connection which minimises impact on wiring as you do not need to cut and join the power cable, avoiding any production loss. The inbuilt Modbus/RTU communication port for RS485 connection, avoids all the standard problems of
analogue signal communications. The CPA series of contactless power analysers are able to measure a comprehensive set of variables such as V, A, W, var, VA, kWh, PF, HZ and THD. This new CPA series is suitable for four different mounting options either DIN, panel mount, vertical, or
horizontal, to suit any installation. The ‘plug & play’ setup ensures ease of setup using Carlo Gavazzi’s UCS (universal configuration software) and is fully compatible with the VMUC-EM energy management solution. The CPA Series ensures optimal performance in industries such as photovoltaic monitoring, battery charging systems, AC and DC motor monitoring, industrial process control, and conventional energy for both commercial and industrial, as well as energy service companies.
Carlo Gavazzi
safety rating ensures safe operation on the supply side to the facility. Current ranges can be up to 2,000A for both AC and DC.
LIGHT WEIGHT FLEXIBLE CURRENT METERS With this type of current measuring device, the fixed jaw of the clamp meter is replaced by a flexible current sensor, linked to a display module for True RMS readings and min/max monitoring. The flexible design enables access to difficult to reachs and large conductors, where conventional clamps won’t go, and it cannot be overloaded by high currents.
LEAKAGE CURRENT CLAMP METERS With the latest designs, it is now possible to measure currents below 1mA to a resolution of 0.01mA, suitable for troubleshooting nuisance RCD tripping, checking for insulation degradation without powering off the circuit, and appliance testing. Having chosen the category of clamp
meter, a simple check list can be used to ensure reliable performance, safe measurement and accurate results for your application. The key features to consider are minimum and maximum current levels, the safety installation category rating for your application, resolution and accuracy for the minimum level of current, jaw size for access and maximum conductor size, and AC only current or AC and DC current. Features for ease of use can include auto ranging, backlight and thumbwheel for function selection, and for additional functionality, AC/DC voltage, resistance and min/max recording to identify peak loads and nuisance tripping, and true RMS measurement to cope with harmonics and distorted waveforms caused by modern low energy lighting systems and power supplies.
www.gavazzionline.com Martindale Electric
www.martindale-electric.co.uk
24 MARCH 2017 | ELECTRICAL ENGINEERING
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