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Choosing a Suitable Vanguard Meter for Low Resistance Measurement

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MicroOhmmeters are devices used to measure junction resistance of joined conductors.The resistance of the junction can tell you the internal condition of the joined metals. But how does junction resistance tell you the condition of metal joints? The gaps in joined conductors may accumulate contaminants like moisture, dirt and grease. These contaminants have a higher resistance compared to the conductors. Since they accumulate in between the joined metals, they introduce resistance. Some electrical components that are prone to junction failures are circuit breaker contacts, distribution transformer terminals, switch gears and relays. The conductors in these components carry high current and corrosion or contaminants can severely affect their current carrying capacity.

In selecting a DLRO or microOhmmeter, you must get one that provides ample current to be able to test very low resistance. It should also have various protective measures for safe operation. If you are undecided on what to get, you might want to check out Vanguard microOhmmeters. Some of the popular models are the Vanguard Auto Ohm and Vanguard DMOM. Here is a comparison of the two models to help you decide which tester is suitable for your needs.

Vanguard Auto Ohm 100 Amperes MicroOhmmeter

The Auto Ohm offers basic microOhmmeter functionality which is suitable for most low resistance measurement applications. It can measure the resistance of bus bars, welded joints and other joined metal conductors that do not need a pure DC test current. It also automates testing which saves you time and effort in getting the right testing range. Other features include:

  •        Can measure resistance from 1 μΩ to 300 mΩ
  •        Variable output current of 10 Amperes to 100 Amperes
  •        Stores the last three results in its memory
  •        Simple to use front panel interface
  •        Controlled rise and fall of test current
  •        Comes with the following accessories

o   Potential current assemblies

o   Power cord

o   Ground Cable

o   Carrying Case

o   Manual

Vanguard DMOM-200 200 Amperes True DC MicroOhmmeter

The DMOM-200 is a suitable meter if you are looking for a device for testing sensitive devices like bus differential relay schemes. This tester has an ultra pure DC output which reduces the generation of magnetic transients induced into the circuit breaker’s current transformer. The reduction of magnetic transients reduces accidental tripping of the circuit breaker. This tester is also ideal for applications that need a controlled rise and fall rate of the output current. 

  •        Can measure resistance from 1 μΩ to 5 Ω
  •        Microprocessor controlled for exceptional accuracy
  •        Variable output test current or 10 Amperes to 200 Amperes in 1 Ampere increments
  •        Variable test current rise and fall rate of 5 seconds to 10 seconds
  •        Automated testing using a sense cable
  •        Dual Ground option which lets you measure contact resistance with both bushing being grounded.
  •        Back-lit 128 x 64 pixels LCD screen
  •        QWERTY Keypad on front panel
  •        Internal memory than can store 64 readings and 999 test records on an external flash drive
  •        Built-in thermal printer
  •        Can be controlled through a PC through an RS232 port for advanced analysis
  •        Can export test results to a computer in Excel, PDF and XML formats
  •        Comes with the following accessories:

o   30-feet test cable set with welding type clamps

o   Case

o   Handspike set

Whether for basic low resistance measurement or for high-powered critical applications, you’ll find a Vanguard microOhmmeter suitable for the job. If you want to evaluate the features of the testers first-hand, consider test equipment rental. This way you can determine if the testers operate as expected in real-world applications. This also helps you get a tester that gives the best value for your money. You do not have to waste money buying a meter and later realize that it doesn’t meet your needs.

Protec Equipment Resources offers affordable rentals and leasing of test equipment. Aside from microOhmmeters, we also carry various low and high voltage testers to cater to your needs. Some of the brands that we carry include Vanguard, Raytech, ABB, Megger, Doble, Metrel, Fluke and more. Please call us at 1-866-352-5550 for more information about our services and for a rental quote.