The use of micro ohmmeters with the 4-wire measurement method is a common procedure in the power field for low resistance measurements (in micro ohms and milliohms range), with the purpose of detecting and preventing future problems; it is performed in breakers, switchgear, busbars joints, switching contacts and critical connections, as well as also used in any other metallic connection checks of other installations in different industries.
The PRIME 600 is a micro ohmmeter that integrates both the contact resistance and the dynamic resistance measurement (DRM) as a stand-alone unit; the dynamic resistance test, which is essential in analyzing the wear of the arcing contacts in SF6 and vacuum breakers, is a function never found before in micro-ohmmeters, so that with the PRIME is not required to combine several equipments for the complete static and dynamic resistance analysis, becoming an ideal option for circuit breaker testing.
The PRIME plot the DRM time/resistant curve that describes the resistance changes on the measured spot throughout a few milliseconds, for detecting contact anomalies and wear; the analysis of the relevant characteristics and values of this curve is an effective diagnostic way of the internal condition of the breaker contacts, and reveals potential problems related to the arcing contact condition without having to open the chamber.
The nature and dimensions of the electrical installations impose the need of accurate, high current injection, with the required high power, for obtaining reliable measurements throughout the entire setup; the injection range of the PRIME reaches up to 600 A with pure DC generation (no ripple), which eliminates resistance distortions in elements with significant inductive characteristic, for example when checking a whole busbar and the resistance measurement could be affected by the nature of the DC injected; this high current micro ohmmeter features the higher power on the market (6 Vdc at 600 Adc) which enables for longer leads, less connections problems, and more accurate measurements.
The PRIME microohmeter provides easy and intuitive use with touch screen and several pre-defined test modes, reducing the testing time; at the beginning of any test, the equipment checks for proper connectivity of the system, warning of possible connection mistakes; for increased safety, the Prime 600 demagnetizes the connected load at the end of each measurement.
The micro ohmmeter includes the easy generation of test reports, with direct printing on field through the built-in thermal printer, or saved to USB or PC with the PrimeSync software for grouping tests in a nice report exportable to office formats in PC.
For higher accuracy and being possible to compare the results measured at determined temperature with the standard values, the option of a temperature sensor, which transmits the temperature of the tested spot to the Prime 600, allows for results normalization in temperature.
An optional dual ground clamp accessory eliminates the need to remove the ground protection and speeds up the measurement process with a dual ground test method.
The high quality of the robust IP67 protective case also ensures safe transport and use in harsh environments.
Dual Ground Operation
The Prime 600 features a derived current input that measures the current flowing across the earth circuit when both sides of the measured point are grounded. The measured value is then suppressed from the resistance calculation. This eliminates the need to remove the ground protection (which is unsafe and not always possible) and speeds up the measurement process.
The user only needs to attach a current/voltage converting clamp (offered as an option) to one of the grounding cables and connect it to the Prime 600’s derived current input. SMC offers a high-quality current clamp, tested and verified for proper Dual Ground operation, among the Prime 600’s optional accessories.
For increased safety, the Prime 600 will de-magnetize the connected load at the end of each measurement.