ground loop resistance Measuring

Grounding - is an electrical connection of an appliance to the ground.

It is necessary to protect people from electric shock in case of malfunction or damage to the appliance.

In the role of earthing is most commonly used conventional metal rod, but can be applied and the complex special form, consisting of complex elements.

To check the quality of the ground using the ground loop resistance measurement.

The principle of

With this measure determine the value of the electrical resistance to earth, which can be reduced if necessaryincreasing the conductivity of the medium or the contact area.

To do this, increase the amount of salts in the soil, using a plurality of metal rods or apply some other methods.

Arrangement of earthing and grounding requirements are regulated by the SAE (rules of electrical equipment and installations).

should know that simple grounding only reduces the voltage phase, which hit the body of the appliance.

In order to protect human life and health, it is desirable to install the grounding device in conjunction with the protective device.

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Earthing device is selected and designed individually for each specific case.

Measuring of ground loop resistance is performed immediately after entering a residential facility or plant into operation.

Further measurements are made once a year.

structure and parameters of the grounding device depend on several factors: the composition and the type of soil, soil moisture, etc.Before setting up the project grounded.

Measured force earthing device resistance by special devices that allow you to identify the specific value of ground resistance accurately and quickly, ground rod, as well as its elements.

grounding resistance can be measured by four-, three- and two-pole methods.For repeated measurement with the unit includes a special pliers.

instruments resistance measurement may take into account various parameters that could affect the course of the measurements, and correct results.

measurement procedure itself

measurement procedure is carried out as follows: after the grounding device artificial short circuit electric current and it produces a voltage drop measurement.

Next to test the grounding rod positioned auxiliary electrode, which is connected to the same supply voltage.

Then the measuring probe is carried out measuring the voltage drop on the first rod.Measurements are made in the zero-potential area.

Such grounding quality measuring method is used more often.

method of measuring ground

resistance grounding resistance should be measured in the summer or winter, when the resistance of the soil takes more importance.

grounding devices resistance values ​​can be different for each individual case, for example, to a private house earthing device resistance value is 30 ohm.

For measurements used effectively two-, three- or four-pole earth resistance measurement method.

When performing resistance measurements should follow the appropriate instructions:

• potential probe for measuring resistance is placed on the test area between the earth electrode and the auxiliary current probe;
• distance from the ground to the grounding of the auxiliary current probe five times the depth of the earth rod or the length of the band electrode;
• with resistance measurements in complex earthing system, this distance is calculated as a function of the greater length of the diagonal, which runs between the individual grounding devices.

In some cases, it may require additional measurement of earth resistance.For example, resistance measurements are carried out in a variety of underground utilities.

In this case, a number of measurements at different distances and directions of rays between the probes.As the actual value is considered the worst result.

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grounding device resistance at any time of the year should not exceed the permitted limit values.

With all of the maximum permissible value can be read using the application 3 (PTEEP) or table 1.8.3 (RB-7).

addition to measuring earth resistance devices should also make measurements of the insulation resistance.

Such measurements will show the condition of the insulation of electrical circuits and electrical equipment.

Methods for measuring insulation resistance and insulation testing standards and checks electrical PUE determined, PTEEP, GOST, etc.

Insulation resistance is measured by a special device - Megger.

This device consists of a continuous current generator with a manual drive, additional resistances and magnetoelectric ratiometer.

Before starting the measurements, check that the test object is no tension.Isolation thoroughly cleaned of dirt and dust, after which the object is grounded for 2-3 minutes.It is necessary to remove the residual charge.

to the test instrument or line megohmmeter attached via separate conductors with insulation having greater resistance, usually not less than 100 megohms.

insulation resistance measurements performed at a stable position of the instrument clockwise.To do this, turn the generator handle quickly and evenly.

exact insulation resistance is determined as indicated by the arrow Megger.After measuring the test object should be discharged.

Prices

Services Measurement of insulation resistance and ground are available in specialized firms or electrical laboratory.

Independently make such measurements are not recommended, as it is very dangerous.Price

measuring ground loop resistance and insulation depends on the complexity of the work, as well as the object distance (travel expenses).

Filling measurement protocol and technical report are included in the cost of testing.Therefore, separately do not have to pay for them.