BM5200 5 kV insulation resistance tester

This battery-powered tester comes with a digital and an analogue arc display

Designed for high voltage insulation resistance testing of cables, rotating plant machinery, transformers, switchgear, and industrial applications

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Three insulation resistance (IR) test modes

Insulation (InS), Polarization Index (PI), and variable timed test (t) modes are available in any IR test range

CAT III 600 V rated with additional safety features

Including high voltage warning indicator, external voltage display after IR test, automatic discharge of reactive loads, and test leads

Guard terminal for accurate results

Helps obtain accurate results when performing tests on items that have significant surface leakage

Perform DC insulation tests

Five test ranges at 250 V, 500 V, 1000 V, 2500 V, and 5000 V covering a measuring range of 100 kΩ to 1000 GΩ

Full Product Details

About the product

The BM5200 5 kV insulation resistance tester has been designed for high voltage insulation resistance testing in the maintenance and servicing of cables, rotating plant machinery, transformers, switchgear, and industrial applications.

With the BM5200, you can perform DC insulation tests at 250 V, 500 V, 1000 V, 2500 V, and 5000 V. Its insulation resistance measuring range is from 100 k Ω to 1000 G Ω. What’s more, it provides an automatic discharge for capacitive circuits under test and displays decaying voltage.

The instrument is not only battery powered, but it also comes with both a digital and an analogue arc display. It also uses a guard terminal to increase the accuracy of its results by minimizing the effects of surface leakage that can lead to measurement errors.

FAQ / Frequently Asked Questions

Why carry out diagnostic insulation testing?

Electrical insulation degrades over time because of the various stresses that are imposed upon it during its everyday working life. The insulation has been designed to withstand these stresses for a period of years; this is regarded as the working life of that insulation and often runs into decades.

Abnormal stresses can bring about an increase in this natural ageing process that can severely shorten the working life of the insulation. For this reason, it is good practice to perform regular testing to identify whether increased ageing is taking place and, if possible, to determine whether the effects may be reversible.

The purpose of diagnostic insulation testing is:

To identify increased ageing
To determine the cause of this ageing
To pinpoint, if possible, the most appropriate actions to correct the situation

While there are cases where the drop in insulation resistance can be sudden, such as when equipment is flooded, it usually drops gradually, giving plenty of warning if tested periodically. These regular checks permit planned reconditioning before service failure, or a shock condition occurs.

Without a regular testing program, any failures will come as a surprise, i.e., unplanned, inconvenient, and will take a great deal of time, resources, and money to fix.

How often should you test?

That depends upon the size and complexity of your plant. Even identical units can differ in the required check periods; experience is your best guide. In general, however, working apparatus – such as motors and generators – are more likely to develop insulation weaknesses than wiring, insulators, and the like.

We recommend establishing a test schedule for working equipment, varying from every 6 to 12 months, depending on the size of the equipment and the severity of the surrounding atmospheric conditions. For wiring and the like, tests once a year are generally sufficient unless the plant conditions are unusually severe.

Why does the accuracy decrease at high levels of insulation resistance?

As the insulation value increases, the test current decreases and becomes harder to measure with the same level of accuracy.

Troubleshooting

Why does a fuse symbol appear at the top of my display?

This symbol indicates that the instrument has experienced an overcurrent causing the fuse to blow. The fuse is in the battery compartment; you can replace it with the spare fuse.

The voltage output is zero on all ranges

A broken standoff between the display and control board will cause zero voltage output on all ranges. Such a break is usually caused by rough handling. You will need to send the instrument for repair in such a case.

Interpreting test results

Insulation resistance readings should be considered relative. They can be quite different for one motor or machine tested three days in a row, yet it does not mean bad insulation. What matters is the trend in readings over a longer period, showing lessening resistance and warning of coming problems. Periodic testing is, therefore, your best approach to preventive maintenance of electrical equipment, using record cards or software to trend the results over time.

Whether you test monthly, twice a year, or annually depends upon the equipment's type, location, and importance. For example, a small pump motor or a short control cable may be vital to a process in your plant. Experience is the best teacher in setting up the scheduled periods for your equipment.

We recommend making these periodic tests in the same way each time. That is, with the same test connections and test voltage applied for the same length of time. Additionally, we recommend performing tests at about the same temperature or correcting them to the same reference temperature. A record of the relative humidity near the equipment during the test is also helpful in evaluating the reading and trend.

Periodic insulation resistance tests

In summary, here are some general observations about how you can interpret periodic insulation resistance tests and what you should do with the result:

Condition	What to do
Fair to high values and well maintained	No cause for concern
Fair to high values but showing a constant tendency towards lower values	Locate and remedy the cause and check the downward trend
Low but well-maintained values	Condition is probably acceptable, but you should investigate the cause of low values
So low as to be unsafe	Clean, dry out, or otherwise recondition the insulation to acceptable values before placing equipment back in service (test wet equipment after drying out)
Fair or high values, previously well-maintained but showing a sudden decrease	Make tests at frequent intervals until you locate and remedy the cause of low values; or until the values have become steady at a lower level but safe for operation

Temperature dependency

The resistance of insulating materials decreases markedly with an increase in temperature. However, we’ve seen that tests by the time-resistance and step-voltage methods are relatively independent of temperature effects, giving relative values.

To make reliable comparisons between readings, you should correct the measurements to a base temperature, such as 20 °C, or take all your readings at approximately the same temperature.

A good rule of thumb is: For every 10 °C increase in temperature, halve the resistance; or, for every 10 °C decrease, double the resistance.

Each type of insulating material will have a distinct degree of resistance change with temperature. Factors have been developed, however, to simplify the correction of resistance values. Please refer to the document linked below to find such factors for rotating equipment, transformers, and cable (Section: Effect of Temperature on Insulation Resistance).

User guides and documents

User guide

BM5200_UG_en-es-pt.pdf

pdf 435.64 KB

User guide

BM5200_UG_EN.pdf

pdf 269.34 KB

Technical guide

MIT500-1_wp_en_V01.pdf

pdf 799.35 KB

Application note

Application-guide-5-k-V,-10-k-V-and-15-k-V-insulation-tester-lead-sets.pdf

pdf 4.06 MB

Technical guide

Above 1kV_InsulationGuide_br_en.pdf

pdf 1.09 MB

Technical guide

StitchInTime_AG_en.pdf

pdf 2.38 MB

Application note

Be-on-guard-for-effective-testing_AppNote_EN_V02.pdf

pdf 2.52 MB

Technical guide

Characteristics-of-insulation-resistance_TG_EN.pdf

pdf 4.2 MB

FAQ / Frequently Asked Questions

How do I use the timed insulation resistance test?

The timed IR test is a test that automatically terminates after a user-adjustable time (t). You can select “SETUP” on the range switch and adjust timer (t) using the up and down arrow buttons to set the desired time, followed by a single press of the PI-t (left arrow) button. Default time (t) is set at one minute because IR1min is frequently referred to in international standards.

When would I use the guard terminal?

For basic insulation resistance tests with little possibility of surface leakage affecting the measurement, it is not necessary to use the guard terminal, i.e., if the insulator is clean and there are unlikely to be any adverse current paths. However, in cable testing, for example, there may be surface leakage paths across the insulation between the bare cable and the external sheathing due to moisture or dirt. To obtain an accurate measurement, particularly at high testing voltages, a bare wire may be bound tightly around the insulation and connected via the third test lead to the guard terminal ‘G.’

What does the polarisation index (PI) tell me?

Polarisation index (PI) test performs a test that calculates the ratio of insulation resistance at ten minutes, IR10 min, to insulation resistance at one minute, IR1 min. This test provides a simple indication of insulation polarisation when subjected to high voltage DC. A high PI value indicates a high degree of insulation polarisation and, therefore, good insulation condition. Generally, the PI value should be two or above.

Polarisation occurs at different rates ranging from minutes to several hours, which led the IEEE to create a ratiometric PI test. The IEEE standard 43-2000, “Recommended Practice for Testing Insulation Resistance of Rotating Machinery,” limits the use of PI test on winding systems to those with IR1 min being less than 5000 MΩ.