Discontinued

S1-568, S1-1068, and S1-1568 insulation resistance testers

Perform accurate insulation resistance measurements in tough, high noise environments

5 kV, 10 kV, and 15 kV high performance diagnostic insulation testers for power utilities and service companies

Find a supplier Get a quote

High noise immunity

Noise rejection of 8 mA - twice that of most comparable instruments – with four user-selectable software filters

Resistance range up to 35 TΩ

Insulation resistance up to 35 TΩ at 15 kV and 10 kV, and 15 TΩ at 5 kV

Safety rated up to CAT IV

Up to 1000 V at altitudes up to 4000 m for the S1-1568, and CAT IV 600 V to 3000 m for the S1-568 and S1-1068 test instruments

Battery and AC operation

Operate with rapid charge Li-ion battery that meets IEC 62133, or AC source when the battery is flat

New PI Predictor™

Obtain 10 minute PI values in typically half the time with the new patented PI predictor

Full Product Details

About the product

The S1-568, S1-1068, and S1-1568 insulation resistance testers from Megger come with class-leading noise rejection of 8 mA – twice that of most comparable instruments – and enhanced software filtering that has four user-selectable options. These DC insulation resistance testers come in 5 kV, 10 kV, and 15 kV and deliver dependable results in even the most severe of electrical environments, including high voltage transmission and distribution substations.

The performance of these groundbreaking instruments has been exhaustively proven in the laboratory and, more importantly, has been convincingly demonstrated in the field. Accurate and consistent results were, for example, obtained in a working 765 kV substation where no other insulation tester had been able to operate successfully.

Megger’s S1 series of insulation testers are available in three models:

The S1-568 tests at up to 5 kV and can measure insulation resistance up to 15 TΩ
The S1-1068 operates at up to 10 kV and measures up to 35 TΩ
The S1-1568 has 15 kV capability and measures up to 35 TΩ

All models have a high short-circuit current of 6 mA to ensure rapid charging of items under test. The S1-568 and S1-1068 have a CAT IV 600 V safety rating, at altitudes up to 3,000 m, with the S1-1568 having CAT IV 1000 V to 4,000 m, in line with IEC 61010.

Other innovative features include the provision for remote control via a fully isolated USB port, which makes the instruments ideally suited for use in production environments, and internal storage for date- and time-stamped results. Stored results can be recalled to the display, downloaded via a Bluetooth wireless link, or accessed via the USB port.

To ensure that testing is never delayed through lack of power, these S1 insulation testers incorporate rapid-charge Li-ion batteries that give up to 6 hours of testing on a full charge for the 5 kV model and 4.5 hours for the 10 kV and 15 kV models. With just 30 minutes of charging from flat, the batteries give around one hour of testing time, and it’s also possible to operate the instrument from an AC power supply even if the battery is completely flat.

Compact and lightweight, the S1 insulation resistance testers feature a rugged dual-case design and, with the lid closed, they have an IP65 ingress protection rating. They offer timed insulation resistance (IR), dielectric absorption ratio (DAR), polarisation index (PI), dielectric discharge (DD), step voltage (SV) and ramp diagnostic tests, as well as a dedicated voltmeter function.

NEW

The patented PI predictor enables you to obtain 10 minute PI values in as little as 3 minutes! The new method starts to predict the final IR curve from 3 minutes into the test and as soon as the predictor is confident with the prediction, the test is stopped and the predicted value of the PI displayed. In most cases, this happens within 5 minutes, meaning the test time is typically halved!

Troubleshooting

The battery symbol on the display’s upper right shows little or no charge

Unfortunately, lithium-ion batteries eventually wear out and can no longer accommodate a charge. This event is a common and, sooner or later, inevitable issue, but fortunately it is easily corrected. Replacement batteries are available from Megger, and you can quickly change one following the instructions in the User Guide.

The tester cannot indicate measurement into the tera-ohm (TΩ) range

Do a visual inspection of the unit, and don’t overlook the lead set. It is understandable to focus on the instrument and take the lead set for granted, but the leads are commonly knocked about from handling more than the instrument. In particular, the strain relief at the end of the lead becomes damaged - its absence is a strong indication that the lead set soon needs to be replaced. Damaged leads tend to affect the most negligible leakage currents first, so the instrument may not be able to indicate measurement into the tera-ohm (TΩ) range. This symptom means that the lead set should be repaired or replaced.

E plus 1 or 2 digits appears on display

These are control and measurement boards post error codes. These appear on the display as “E” followed by a 1- or 2-digit number. The User Guide gives brief definitions. These are not user-adjustable. They indicate component failures or calibration resets that a Megger repair technician or authorised repair centre must perform.

The charge circuit will not work

This symptom indicates that the power supply transformer has broken off the power supply board, usually due to rough handling and/or dropping. The transformer, being relatively heavy, will come loose from its mountings. This breakage interrupts or terminates power to the circuitry, resulting in a ‘dead’ instrument. Contact your local Megger repair technician or authorised repair centre.

Can I reset the S1 to its default settings?

Yes - remove the S1 from the AC source. Press both the “OK” and backlight buttons while switching the main rotary switch from the “OFF” position to the “settings” icon.

Why does the display say “brd”?

Insulation tests are automatically stopped in breakdown mode, and “brd” is displayed when a fault causes the applied voltage to drop rapidly. Burn mode IR tests ignore breakdown and continue to test the insulation and are, therefore, destructive tests. Burn mode is used to purposely create a carbon track in insulation to facilitate fault location.

Interpreting test results

General

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 SW 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.

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 to halve the resistance for every 10 °C increase in temperature 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 "Stitch In Time" to find such factors for rotating equipment, transformers, and cables (Section: Effect of Temperature on Insulation Resistance).