The equipment for measuring contact resistances: Microhmmeters

Microhmmeters are used for measuring contact resistances in high-voltage breakers, knife-contact fuses, disconnecting switches (isolators), bus-bar joints, line joints, etc.

Excessively high contact resistance frequently causes switchgear breakdowns at breakpoints and bus-bar joints. Overheating risks are becoming more acute in today's distribution networks as they carry heavier loads. It is highly important to check contact resistances at regular intervals and detects faults before they cause overheating.

In any power transmission/generation installation, periodic checks are part of the routine even if you use a good HV circuit breaker. Damaged or poorly maintained contacts can lead to single phasing, arcing and even fire. Hence, it is highly important to perform regular checks with accurate measuring equipment.

The heart of any Microhmmeters is the combination of two main circuits:

Microhmmeter QAuto Ohm 200 S3 by Amperis

Microhmmeter by Amperis has been developed to offer a wide choice of solutions for a low resistance measurement. The QAuto Ohm 200 S3 by Amperis is a class apart on world markets. Designed in a rugged and compact form, this Microhmmeter is ideal for field work. The QAuto Ohm 200 S3 Series is designed ensure safety, ease of use and versatility in mind. Amperis offers a full range of circuit breaker equipments. The Microhmmeter can be easily used anywhere to measure a low resistance value with a high degree of accurateness.

This Microhmmeter is lightweight and microprocessor based and can test contact resistance, bus contact joints or any other low resistance measurement. It can also be used to test the rise and fall rate of current. It can store data for over 100 tests that is extremely useful in keeping track of wear and tear of components.

The QAUTO-OHM 200 S3 Microhmmeter controls the test current’s rise and fall rate. The rise and fall rate of test current can be selected from 5 seconds to 30 seconds. There is an “Auto Test” mode also available, and the mode can be initiated simply by applying the sense cables’ leads at the two points of interest in the current path. The feature of "Auto Test" is very convenient while measuring a sequence of several resistance values in a circuit breaker contact.

To improve the quality of products, companies need to know the exact resistance value of the contact, a winding, a connector. Microhmmeters by Amperis are particularly suited for this type of test as well as for measurements of:

The long-term stability of measurement depends on the stability of reference semi-conductors and the resistance quality in the reference circuit of the Microhmmeter. Amperis uses precision resistances that have undergone long aging cycles in order to guarantee their long-term stability. Microhmmeters by Amperis are specifically designed for measuring contact resistances in circuit breakers, bus-bar joints, disconnecting switches, and other such devices.

The Microhmmeter by Amperis are easy to understand and operate. The Microhmmeters have QWERTY interface with an easy to read LCD screen. The LCD screen gives proper readability even in bright sunlight. Along with that, there is 30ft test cable among other useful features. A significant advantage of the Microhmmeter QAuto Ohm 200 S3 by Amperis is its user-friendly interface and high portability, especially when they are used on-site. The compact design makes the device easily carried anywhere within the site. The equipment is designed in an ultra-protective way and can be used in any weather. The equipment's LCD display with a menu for all control functions provides high readability to the users; this ensures a hassle free way of operation. The Microhmmeter by Amperis are your ideal companion on field work. The ease and simplicity of operation by Amperis devices make them highly recommended and the best choice by the users. Know more about the technical specifications of the product here.