Here are the answers to some frequently asked questions.
If you can’t find the information you want here, please get in touch


What can be tested with the ISOTEST act?

The ELMED ISOTEST act testing devices are compact all-in-one models (control and high-voltage generation in a compact housing) for non-destructive testing for non-porosity by means of  high-voltage testing.

Even the smallest defects can be detected with the high-voltage test. Defects can be pores, cracks or weak points.

The test voltage has to be selected individually considering the coating thickness and the material to be tested as well as common standards and manufacturer’s specifications.

Testing systems are available with pulse voltage as well as DC voltage for fulfilling the different standards and manufacturer’s specifications.

The following tests are possible:

  • Detection of defects in electrically non-conducting or slightly conducting coatings on electrically conducting carrier materials.
    A typical application is the testing of factory coatings on steel pipes.
  • Detection of defects / porosity in electrically non-conducting materials.
    Typical applications are the testing of film webs or plates as well as the testing of plastic tubes and pipes.

Are ISOTEST act holiday detection systems designed for continuous operation?

Thanks to their robust and sophisticated construction ELMED‘s ISOTEST act test devices are designed for continuous operation.

What is the proper grounding?

Depending on the individual requirements the following grounding options can be applied:

1. Direct grounding

Direct grounding is basically used for high-voltage testing with DC voltage.

Normally, brush electrodes with an electrically highly conducting and sufficiently long wire fill (earth electrode) are used for a proper grounding

Typical grounding electrodes:
Flat / strip brushes with a trimming made of brass or VA.
The grounding electrodes must have a low impedance contact with the metallically blank area of the test object during the entire high-voltage test.

2. Special forms of direct grounding
2.1 Testing of film webs or plates made of non-conducting material

The grounding method described below can be used in high-voltage testing with DC voltage as well as with pulse voltage.

For testing film sheets or plates a highly conductive and low resistance grounding slip table (grounding electrode)  has to installed underneath the test electrode. The surface area must imperatively be larger than the supporting surface of the test electrode(s) in order to ensure that in case of a pore high-voltage spark is produced (voltage impact).

2.2 Testing of plastic tubes and pipes

The grounding method described below can be used in high-voltage testing with DC voltage as well as with pulse voltage.

To test plastic tubes and pipes, these must be drawn over a good conducting and low impedance, grounded round material (grounding electrode).

In the area of the test electrode, the air gap between the inner side of the test object and the round material must be kept as small as possible. The round material must be located under the total supporting area of the test electrode.

3. Capacitive grounding

This grounding method can only be used for high-voltage testing with pulse voltage.

Direct grounding of the test object is not possible in capacitive grounding. A metallic connection between the grounding electrode and test object is not required.

Typical applications of capacitive grounding:

  • Testing the factory jacketing of steel pipes
  • Testing fully-coated test objects

3.1 Practical execution of capacitive grounding with coated steel pipes

Brush electrodes in the form of flat / strip brushes with a trimming made of brass or VA are installed below the pipe both in front of and behind the test electrodes of the high-voltage testing equipment (grounding electrodes).

The number of grounding electrodes to be installed (in front of and behind the high-voltage testing equipment) and hence, their supporting surface on the coating of the pipe depends directly on the used test electrodes.

The ratio of the supporting surface of the grounding electrodes to the supporting surface of the test electrodes must be at least 10:1.

The grounding electrodes are normally combined in the form of packets (3-5 pieces) and mounted between the rollers of the conveyor so that their height can be adjusted.

Contrary to the test electrodes, the trimming material of the grounding electrodes must lie clearly on the coating of the pipe.

What kind of work safety does the ISOTEST act holiday detector system offer?

All ISOTEST act testing systems have been designed and constructed having taken into account a risk analysis and careful selection of the harmonised standards as well as further technical specifications to be observed.  They fulfil the requirements of the Equipment Safety Act and are therefore state of the art technology and guarantee maximum safety.

All ISOTEST act testing systems have a CE mark.

The high safety standard guarantees that the user is protected in the best possible manner while working with high voltage.

  • For testing devices with pulse voltage, the potential risk is conspicuously below the permissible thresholds according to IEC No.479-1 and 479-2.
  • For testing devices with DC voltage, maximum possible safety is achieved by limiting the test flow

How can the functions of the test device be externally monitored?

The voltage-free, actuated changeover contact (X6.1 and X6.2 open, X6.2 and X6.3 connected) for device monitoring displays that the device is working properly.
In case of fault – including power failure - the contact falls (X6.1 and X6.2 connected; X6.2 and X6.3 open).

How can a detection of a pore be evaluated with the ISOTEST act?

External alarms (siren, rotary reflector lights) can be connected directly to the live terminals X5.1 and X5.2 for evaluating the pore display.

The voltage-free changer contact (X7.1-3) of the pore display is confirmed when sparking occurs when moving over a defect.

Can the ISOTEST act holiday detector be operated be remote control?

The outer control can be used to interrupt the test e.g., for pipe intermediate spaces (contact open / no control voltage). Unlike the limit switch, the test is reactivated immediately after enabling.

How is the ISOTEST act holiday detector activated?

Auto Start is activated by switching the mains switch on the housing front to Position “1”. The control lamp in the mains switch as well as the green signal lamps on the housing front light up. The internal check and calibration operation are completed after app. 10 seconds, the mode (master or slave setting) appears on the display for about 2 seconds and the yellow signal lights up. The testing device is activated.

How do I have to store the ISOTEST device when it is not used for a longer period of time

If the testing system is not used over a longer period of time, please take the following measures:

  • Disconnect the testing device(s) from the mains.
  • Clean the testing devices and high-voltage testing equipment and protect them from dirt.
  • Protect the accessories e.g., testing or grounding electrodes from damage by suitably storing in dry rooms.



ISOTEST® In-Plant Holiday Detectors

ISOTEST act 8.0 / 35


In-plant Holiday Detector ISOTEST act 8.0 / 35

Testing of coatings, foils and rubber coatings



In-plant Holiday Detector ISOTEST act P2

Testing of FBE / 3 layer PE / PP tube coatings



In-plant Holiday Detector ISOTEST act DC

Testing of sensitive coatings such as epoxy and Rilsan

+49 2056 9329-0

Laatste Nieuws:

Available for you as usual!

Due to the situation caused by the Coronavirus-COVID-19 pandemic, we ...