Vanguard IRM-5000P - Manual (Page 6)

IRM-5000P USER’S MANUAL REV 2
2
1.0 INTRODUCTION
1.1 General Description and Features
The IRM-5000P is a microprocessor-based, high-voltage, insulation-test ohmmeter. The rugged
and portable IRM-5000P is ideal for use in electric utility substations and for industrial
applications.
This sophisticated insulation tester uses a dual-microprocessor design. One microprocessor is
dedicated to the control of the power supply and measuring circuitry, while the second is
dedicated to the user interfaces and printer control. To ensure operator safety, the
microprocessors communicate via an optical link, thus isolating the operator controls from the
dangerous high test voltages inside the unit.
The IRM-5000P measures the insulation resistance of a test material by applying a known test
voltage and measuring the resultant leakage current. The measured insulation resistance is
then displayed on the back-lit LCD screen. The IRM-5000P’s built-in 2.5-inch wide thermal
printer can print test reports in both tabular and graphic formats. Up to 100 test reports can be
stored in the unit’s internal memory. Test reports can also be transferred to a PC via the built-in
RS-232C interface. The IRM-5000P can automatically perform industry-standard tests such as
Polarization Index (PI) test, Step Voltage (ST) test, and Dielectric Discharge (DDS) test.
Test Voltage
The IRM-5000P can perform tests with preset voltages (500, 1000, 2500, 5000 Vdc), or with
user-selectable voltages ranging from 50 Vdc to 5000 Vdc with a ±2 Vdc resolution.
Insulation Resistance Test
The test voltage for an insulation resistance test can be user-selected, and the test duration can
range from 1 to 90 minutes. The IRM-5000P will then collect resistance readings throughout the
selected test period. The resistance value, test voltage, leakage current, and capacitance are
displayed on the back-lit LCD screen. The tabulated test report can be printed on the built-in
2.5-inch wide thermal printer. The report can also be printed as a graph of the resistance over
time.
Polarization Index (PI) Test
The Polarization Index (PI) measures the ratio of insulation resistance after one minute and
then after ten minutes. The Polarization Index is derived from a ratio of the two periods, where
the resistance value at ten minutes is divided by the resistance value at one minute.
PI tests can be run at preset voltages (500, 1000, 2500, 5000 Vdc) or at a user-specified voltage
from 50 Vdc to 5000 Vdc. Test results can be printed in both tabular and graphic formats.
Step Voltage (SV) Test
The Step Voltage test is based on an ideal insulator producing the same resistance
measurement at all voltages. As an example, an insulator that is over-stressed will measure
lower resistance values at higher voltages. Accordingly, the resistances measured on an over-
stressed insulator at increasingly higher voltages (steps) will produce decreasingly lower
resistance values.