The Vanguard Auto-Ohm’s operation is based on the electrical relationships described by Ohm’s law: R=V/I, where I is a known current and V is the dc voltage measured across the unknown resistance (typically, a circuit breaker’s contacts).
Since the current (user selected) through the unknown resistance is known and the voltage across the unknown resistance is measured by a precision voltmeter, the resistance read-out can be calculated using Ohm’s law.
The Vanguard Auto-Ohm test voltage is supplied by a true 5Vdc power supply. The true DC test current is selectable in 2-amp steps, from 10 to 100 amperes for the Auto-Ohm 100 and from 10 to 200 amperes for Auto-Ohm-200. The test current is automatically ramped up and down slowly. This current ramp rate is programmable from 5 seconds to 30 seconds. The voltmeter test leads run separately from the current-bearing test leads to the resistive load thus eliminating any I•R voltage drop error in the current cables.
These Auto-Ohm features make very precise micro-ohm measurements possible without having to calculate compensations for current lead resistance errors.
Vanguard Auto-Ohm 100 Ampere Micro-Ohmmeter
The Auto-Ohm 100 Ampere Micro-Ohmmeter features microprocessor-controlled measuring of very low resistances ranging from 1 micro-ohm to 300 milli-ohms with high accuracy.
Vanguard Auto-Ohm-200 S3 Ampere Micro-Ohmmeter
The Auto-Ohm-200 S3 Ampere Micro-Ohmmeter is a microprocessor-based, true DC micro-ohmmeter. It is designed for testing EHV circuit-breaker contact resistances, bushing contact joints, welding joints, or for any low-resistance measuring application.
Protec Equipment Resources offers a wide range of Vanguard equipment for rent, lease or purchase.
Each Protec office maintains a full complement of electrical test and measurement equipment. Offering equipment from all of the premiere manufacturers for rent, lease or purchase, Protec has the electrical testing equipment you need to get the job done.
