Tinker & Rasor RF-IT - Above Ground Insulator Tester

The Model RF-IT is a highly sensitive device used to test above ground pipeline insulators. The Model RF/IT Insulator Tester is effective in the testing of pipeline insulators in parallel or series installations, even if one or more of the insulators are not operating properly. The tests conducted are fast and accurate.

This unit can also be used for flange bolts shorts. The automatic RF-IT allows the operator to pinpoint the precise contact point. The RF-IT emits an audible beep, and when the operator gets closer to the point of contact, the unit starts beeping faster. At the same time, the sliding scale LCD meter moves from right to left.

Testing methods

Two common methods used to measure a pipeline insulator are DC resistance and Radio Frequency Skin Effect. Radio Frequency Skin Effect is the phenomenon where the apparent resistance of a conductor increases as the frequency increases. With DC, the charge carriers have an even distribution throughout the area of the conductor. However, as the frequency increases, the charge carriers subsequently move towards the edge of the wire, decreasing the effective area and increasing the apparent resistance.

Because the Radio Frequency meter does not use a DC voltage, it is unaffected by DC or AC voltages under 50 volts and there is no need to disconnect the cathodic protection voltage applied to the pipe and/or structure. Another advantage of the skin effect is that errors due to diameter, relative permeability of the pipe and insulator distance are negligible.

To measure an insulator using the Radio Frequency method is similar to that of the DC measurement. The probes are placed across the insulator and the technician reads the display. Maximum deflection of the meter (100 or all the way to the Right) indicates a resistance of a high enough value as to indicate a good insulator, whereas if the insulator is shorted or has a low electrical resistance, the meter will only show reads to the left of top center (older analog meter shows one or two bars from the Left).