FAQ

Here are the answers to some frequently asked questions.
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What can be tested with the ISOTEST holiday detectors?

ELMED ISOTEST test equipment has been exclusively designed for mobile testing of non-porosity of non-conducting or semi-conducting materials. By using a high-voltage tester, even the smallest voids can safely be detected, i.e. pinholes, cracks or weak spots.

What steps are necessary before testing?

Before testing, the device under test as well as the ISOTEST test equipment must be grounded. Subsequently, a suitable testing electrode is moved in close distance to the device under test across the latter's entire surface. The test voltage applied to the testing electrode should be chosen according to the coating thickness as well as the relevant standards and manufacturer specifications. A void is detected by sparking between the testing electrodes and the electrically conductive carrier material as well as an acoustic and visual alarm.

How are pores or cracks indicated?

A void is detected by sparking between the testing electrodes and the electrically conductive carrier material as well as an acoustic and visual alarm.

What kind of safety standards does the ISOTEST offer?

The high safety standards guarantee that personal is protected from electric shock hazards. Potential hazards resulting from pulse voltages in the ISOTEST are clearly below the allowable limits of IEC 479-1 and IEC 479-2.

Patients with pacemakers must not use this insulation testing equipment!!

All ISOTEST test equipment carries the CE label and meets the requirements of all relevant standards and specifications (DIN EN/ISO, DVGW, etc.)

What does the term „test voltage“ mean

The magnitude of the high voltage in kV used to perform the tests. It depends on the type and the thickness of the material to be tested. The following documents contain information about the magnitude of the test voltage:

  • DIN standards
  • EN standards
  • worksheets
  • documentation of coating manufacturers

When testing with the ISOTEST the so called pulse voltage is applied.
Pulse voltage is a gated DC voltage. Unipolar high-voltage pulses ensure maximum testing safety with minimum materials stress and without electrostatic charge of the device under test.

Must the test object be grounded?

To enable safe porosity tests with high voltage, both the ISOTEST test equipment and the device under test shall be grounded. Independently of the grounding method, all electrical connections should exhibit the lowest resistance possible. The contact surfaces for attaching the clamping tongs should be free from contamination and stain.

What is the proper grounding?

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

1. Direct grounding

Direct grounding is used when the grounding conductor can be connected to a contact surface free from contamination and stain.

Required accessories:

  • Standard grounding cable with plug and clamping tongs - Part number: 0174320000
  • Grounding cable, length of 15 m, with plug and clamping tongs - Part number: 0174200100

Type:

  1. Connect the plug of the standard grounding cable to the grounding receptacle of the ISOTEST test equipment.Connect the clamping tongs at the other end of the grounding cable to the device under test.
  2. Connect a pair of clamping tongs of the second grounding cable (part number 0174200100) to the device under test. Connect the second pair of clamping tongs to a ground terminal.
  3. Turn the ISOTEST test equipment on and perform the high-voltage test.

 

Alternatively

Required accessories:

  • Grounding cable Y – type (clamping tongs - clamping tongs/plug) - Part number 0174250010

Type:

  1. Connect the plug of the Y grounding cable to the grounding receptacle of the ISOTEST test equipment.
  2. Connect the clamping tongs at the other end of the grounding cable to the device under test. Connect the second pair of clamping tongs to a ground terminal.
  3. Turn the ISOTEST test equipment on and perform the high-voltage test.

 

Alternatively

Required accessories:

  • Standard grounding cable with plug and clamping tongs - Part number: 0174320000
  • Grounding rod with cable, 2 m - Part number: 0174200000

Type:

  1. Connect the plug of the standard grounding cable to the grounding receptacle of the ISOTEST test equipment. Connect the clamping tongs at the other end of the grounding cable to the device under test.
  2. Connect the clamping tongs at the cable from the grounding rod to an accessible area of the device under test.
  3. Deeply bury the grounding rod in the soil. If the soil is dry, thoroughly water the respective area to obtain a low-resistance connection.
  4. Turn the ISOTEST test equipment on and perform the high-voltage test.

 

2. Special grounding methods Testing plastic material

In most cases, welding seams will be tested when testing plastic material. To allow using the high-voltage test method, coat the welding seam and/or area with a electrically conductive material (grounding electrode).
Attach a grounding electrode to the entire rear of the area to be tested. Pinholes and voids will safely be detected by sparking between the testing electrode and the grounding electrode.

Required accessories:

  • Grounding foil - Part number 0174500100
  • Grounding cable Y – type (clamping tongs - clamping tongs/plug) - Part number 0174250010

Type:

  1. Cut the grounding foil to the required size. Tear off the protective foil by holding at the edges, and fold one corner. Glue the remainder of the grounding foil to the entire rear of the welding seam or area to be tested, press against the device under test, and remove all air bubbles by wiping. Remove the protective foil step by step.
  2. Connect the plug of the Y grounding cable to the grounding receptacle of the ISOTEST test equipment.
  3. Attach a pair of clamping tongs at the grounding cable to the folded corner of the grounding foil, and attach the second pair of clamping tongs to ground, ensuring a low-resistance path. To obtain safe stress relief for the clamping tongs at the folded corner of the grounding foil, secure the grounding foil with adhesive tape, e.g., friction tape.
  4. Turn the ISOTEST test equipment on and perform the high-voltage test. Remove the grounding foil after the test.

 

As an alternative to the grounding foil described above, you can also use electrically conductive fleeces, grounding mats or grounding sleeves made of electrically conductive rubber for the testing of plastic parts.

The leakage test of containers can be performed using electrically conductive liquids, e.g., saltwater, acids, etc. Grounding brushes are available for cylindrical devices under test.

 

3. Indirect grounding through the soil

Indirect grounding is used where the distance between the device under test and a suitable grounding terminal is greater than 15 m. Typical examples are completely muffled pipelines.

Required accessories:

Trailing ground wire - Part number 0174120000
Grounding rod with cable, 2 m - Part number 0174200000

Type:

  1. Connect the plug of the trailing ground wire to the grounding jack of the ISOTEST test equipment. Spread the bronze spiral of the trailing ground wire (6.5 m) on the soil in full length.
  2. Connect the clamping tongs at the cable from the grounding rod to a non-insulated area of the device under test.
  3. Deeply bury the grounding rod in the soil. If the soil is dry, thoroughly water the respective area to obtain a low-resistance connection.
  4. Turn the ISOTEST test equipment on and perform the high-voltage test..

 

Indirect grounding can only be used if the following conditions are met:

  • the device under test is grounded
  • because of its characteristics, the soil exhibits the required conductivity
    - all types of moist soil are suitable
    - unsuitable are, e.g., dry sand, asphalt and flags.

 

4. Capacitive grounding

Capacitive grounding is used where direct or indirect grounding is not possible. This is the case when the device under test has metal carrier material that is inaccessible or consists of completely coated material.

a) Grounding of coated devices under test, using grounding sleeves

Commonly used devices under test are pipelines that have been coated in the field after repair and are subject to high-voltage testing. As there is normally no possibility of direct or indirect grounding, grounding sleeves offer the only possibility of proper and safe grounding.

Required accessories:

  • Grounding sleeve, type 1, for DN 100 - 200 - Part number 0174401020
  • Grounding sleeve, type 2, for DN 200 - 400 (alternative) - Part number 0174402040
  • Grounding sleeve, type 3, for DN 300 - 600 (alternative) - Part number 0174403060
  • Grounding sleeve, type 4, for DN 500 - 1000 (alternative) - Part number 0174450100
  • Grounding rod with cable, 2 m - Part number 0174200000

Type:

  1. Wrap the grounding sleeves around the pipe and secure with the lashing strap. Actuate lever at the lock of the clamping band, and feed the belt from below. Release the lever and tighten the belt.
  2. Deeply bury the grounding rod in the soil. If the soil is dry, thoroughly water the respective area to obtain a low-resistance connection.
  3. Attach the clamp at the cable of the grounding rod to one of the bolts.
  4. Connect the plug of the standard grounding cable to the grounding receptacle of the ISOTEST test equipment. Connect the clamping tongs at the other end of the grounding cable to the second bolt of the grounding sleeve. The bolts should be free from contamination and stain.
  5. Turn the ISOTEST test equipment on and perform the high-voltage test.

 

b) Grounding of completely coated devices under test by using grounding foil

Required accessories:

  • Grounding cable Y – type (clamping tongs - clamping tongs/plug) - Part number 0174250010
  • Grounding foil - Part number 0174500100

Type:

  1. The ratio of the areas of the testing electrode to the grounding foil is smaller than 1 : 10. This means that the contact area of the electrodes must not exceed 10% of the foil area. Cut the grounding foil to the required size. Tear off the protective foil by holding at the edges, and fold one corner. Glue the remainder of the grounding foil over the entire surface and remove all air bubbles by wiping. Remove the protective foil step by step.
  2. Connect the plug of the Y grounding table to the grounding receptacle of the ISOTEST test equipment. To prevent inadvertent pulling of the plug, hook up the stress relief attached to the grounding cable to the snap link at the equipment bag.
  3. Attach a pair of clamping tongs at the grounding cable to the folded corner of the grounding foil, and attach the second pair of clamping tongs to ground, ensuring a low-resistance path. To obtain safe stress relief for the clamping tongs at the grounding foil, secure the clamping tongs with adhesive tape, e.g., friction tape.
  4. Turn the ISOTEST test equipment on and perform the high-voltage test.
  5. Remove the grounding foil after the test.

What is phantom grounding / capacitive grounding?

„Phantom grounding“ or capacitive grounding is the grounding of completely coated devices under test by employing the capacitor method. In combination with suitable accessories, the pulse-shaped voltage in the ISOTEST test equipment allows grounding of the device under test without a galvanic connection.

How can I check the function of the ISOTEST?

Before beginning with the tests, establish contact between the testing electrodes and the grounding terminal with the test voltage enabled. When approaching the grounding terminal, sparking should be observed. The distance at which sparking occurs depends on the adjusted magnitude of the test voltage. Alternatively, the functional verification can be performed on a test pore. At the moment of the flashover the acoustic alarm must be audible and the LED on the membrane-switch front panel must be lit in red.

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

If the test equipment is not used over more than 1 week, the following measures should be taken:

  • Remove the rechargeable battery from the test equipment and connect to the battery charger. Complete discharge can be avoided by connecting the rechargeable battery to the battery charger.
  • Clean the test equipment and the accessories.
  • Protect the test equipment and the accessories from damage by storing in a dry room.

To avoid condensation at temperatures below the dew point, ensure that the equipment is stored at normal ambient temperature. Storage temp.: -20°C to +50°C (Heat timing constant: > 10 K/h)

Is it possible to test wet or damp surfaces with the ISOTEST?

The filter function of the ISOTEST allows an electronic matching to different, capacitive loads.

The load conditions depend on:

  • type and thickness of the material to be tested
  • environmental effects such as humidity
  • type and size of the testing electrode

The tests should be started with filter stage "Standard" (ISOTEST 4S) or „0“ (ISOTEST inspect). If a continuous acoustic alarm is audible after touching a non-porous device under test with the testing electrode, a higher filter stage should be selected until the continuous acoustic alarm is stopped.
If the filter is set to its maximum and the continuous acoustic alarm is still audible, the load conditions should be changed by using a different testing electrode or by drying the device under test. Selecting the filter stage does not affect the magnitude of the adjusted test voltage.

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