Advice 1: How to measure earthing resistance

In our everyday life is part of an increasing number of electrical appliances be it a microwave or a washing machine, a computer or a kettle, for the safe operation of which requires grounding. To make the ground easy, only needed an effective way to check its settings. Consider the functional variant.
You will need
• A device for measuring resistance M416, 2 auxiliary electrode, 2 wires with cross-section of 3.5 square millimeters with a length of 40 m Diameter electrode 16 mm, length 0.6 m.
Instruction
1
Place the auxiliary electrodes connect and check the earthing to the device M416 according to the shown scheme.
2
Hammer auxiliary electrodes into the ground to a depth of not less than 0.5 m blows vertically, not swinging them and loosening the ground around them. To increase the precision of the measurements (to reduce the resistance between the auxiliary electrodes and the ground) wet with salt water the ground around the auxiliary electrodes or increase of their number. Extension rods hammer at a distance of not less than 2 metres between them. The rods, forming a single auxiliary circuit, connect with each other electrically.
3
During measurement, place the device horizontally as close as possible to the measured circuit ground to reduce the length of the wire connecting the circuit ground to the device. This will reduce the measurement error introduced by this wire.
4
To measure resistance, do the following steps:1. Switch B1 is put in the position of ×1.
2. Press the button and rotate the handle "slidewire", ensuring the maximum approximation of the arrow to zero position.
3. The result of the measurement read from the scale of the slidewire, not forgetting to multiply it by a multiplier set by the handle B1.
If the measurement result is greater than 10 Ohms, set the switch of the multiplier of B1 in the next higher position and repeat measurements according to items 2 and 3.
This method is called the "Principle of reduction potential 3-point scheme" and is the best option to achieve acceptable measurement accuracy using relatively inexpensive equipment.

Advice 2: How to make grounding in the Khrushchev

Additional grounding may be required in order to get rid of low frequency hum at 50 Hz. A roar "leaks" in the audio path and interferes with the normal perception of sound mixing console, guitar or computer. In addition, grounding is required when installing household appliances – washing machines, electric cookers, etc.
You will need
• - thick multi-strand cable;
• - screws;
• - washer;
• - metal rod or crowbar;
• - drill;
• cutters;
• - pliers;
• - screwdriver;
• key from the electrical panel.
Instruction
1
If you live in a two - or five-story house built in the mid-twentieth century (the so-called "Khrushchev"), try to find near the landing Board. He may have closed. In this case, consult your responsible for the flap to residents or electrical housing Department and take the key.
2
If the shield is grounded, reaching for him out of the apartment. Take a thick stranded cable and route it from the appliance (or sockets) to the electrical panel. Open the shield and find the place where the body is bolted a lot of wires.
3
Strip the cable end 2 to 3 cm, divide the braid into two pieces, insert between them a screw (for a tighter contact can get him the puck). Using the pliers twist the ends of the braid, creating a tight circle. Screw the screw into the hole located in the electric panel so that it sat tightly enough.
4
The other end of the cable is also clean. In the computer, washing machine, cooker or other equipment, find a place to ground back to the metal chassis, and attach it to the wire by a small screw. Generally, the location of grounding is indicated by the inverted "T" with an additional hatch at the bottom or Ground (GND). Perhaps next to the icon you'll see a clip or special attaching bolt.
5
In order to ground the outlet, connect the cable to special third contact intended for this purpose (it is in all European sockets).
6
If you are found in the entrance of the electrical panel with the possibility of grounding, go down to the basement. Often grounding in the Khrushchev is at the opening switchboard, located in the basement. In this case, route the cable from his apartment to the shield (the keys to the basement and Board-ask in the office).
7
To the first floor there is another option – remove the ground wire through the window. Take a metal rod with a length of 1.5-2 meters, for example, scrap, with one side drill a hole for the screw. Hammer the rod into the ground with sledgehammers, and in the remaining part of the screw the screw with the twisted wire. To improve the conductive quality of the earth, dissolve in a bucket of water, a pound of salt and pour it into the place where I buried the pin.
In any case it is not necessary to do grounding in the Khrushchev through the heating pipes, sewage pipes, balcony railings. It is forbidden by the safety rules of electrical installations.

Advice 3: How to measure resistance with a tester

There are three types of devices which can measure the resistance: a digital, dial, and bridges. Methods of using these gauges differ. An experienced handyman should be able to measure resistance, using any of them.
You will need
• digital multimeter, analog tester, ohmmeter or bridge resistance meter.
Instruction
1
Regardless of the devices you are going to use a resistor, the resistance of which is measured, should be desoldering from the circuit. First it should be unplugged from power source and discharge any capacitors in it.
2
To measure resistance with a DMM, select switch mode resistance measurements and the coarse mode. Wire turn in a socket device corresponding to the measurement mode of resistance, and then connect to the probe resistor. If measured resistance is not a resistor, and the element whose conductivity depends on the direction of current, note that the DMM red probe there is a positive voltage.Sequential shift switch in the direction of more precise limits to achieve the disappearance of the overload. Read indicator, and the position of the switch find out what units they are expressed.
3
Resistance measurement switches the tester is the same, but with a number of its features, namely:- switch the tester in the ohms positive terminal in most cases is on the black test probe;
- zero the scale resistance is at its end;
- after every shift limit the probe device must be closed, put an arrow special controller to zero, and only then carry out the measurement;
- some switch testers range is carried out not by turning the handle, and a permutation of the plug;
also some gauges require, in addition to range, enable measurement of resistance by a separate switch.
4
Bridge meter use. Connecting it to the resistor, move the switch limits in one of these extremes. Rotate the knob from one end of the scale to another. If the indicator of the balance bridge (lighting, sound or pointer) never worked, choose a different limit. It again scroll the slider from one end to the other. This operation is repeated until then, until the bridge do not balance. Now, on a scale on the controller to determine the resistance, and the switch position of limits - in what units it is expressed.

Advice 4: How to measure resistance with a multimeter

Sometimes a situation arises when you need to measure the resistance of the power cord (possible breakage) or to test the fuse, bulb, faulty heating element, and the like. With the help of multimeter these tasks are easy.
You will need
• multimeter, test leads with probes (supplied with the multimeter).
Instruction
1
Insert the test lead black to the COM terminal of the multimeter, then plug the test lead red to the VΩmA socket. Turning the switch of the measuring range, turn the unit on. For measurements of small resistance, turn the switch in the Ω sector and put in position opposite the numeral 200 (measurement Range 0.1 – 200 Ohms). Short between the probes (to check the measuring circuit on the circuit), the display should show the numeric value in the range 0.3 – 0.7. This resistance measuring wire. Each time the multimeter check the resistance value of the measuring wires. When it increases to 0.8 Ohms, replace the test leads. With open-loop wires, the display should show the digit 1 in the leftmost register (very high resistance infinity).
2
To measure touch both contacts in the test circuit. If the chain or the consumer current is OK, the multimeter readings will change: it will show some resistance. In the case of a test for an open in the power cord, fuse or "continuity" of the wires, the resistance should be very low (in the range of 0.7 – 1.5 Ohm). But when checking the electrical consumers (lights, heating elements, winding network transformers) may rise to 150 – 200 Ohms. Moreover, this dependence can be traced – the more powerful the consumer is current, the less resistance.
3
If multimeter readings do not change, switch the measuring range of resistance, put the switch in front of 2000 numbers (0 – 2000 Ohms). And then if the display does not change, switch to the next range and measure again. Note: when the lock opposite numbers 2000K sensitivity of a multimeter is very high and if at the same time take his left and right hands for the contact probe, the instrument will show the resistance of the body that will distort the readings on the multimeter.
Note
All check the circuit and the loads must be disconnected!
Before each measurement, check the measuring circuit for a short. Do not forget to check the battery status: when the device and put the battery the display will show the battery symbol.

Advice 5: How to measure insulation resistance

For measuring the resistance of the insulation , use a megger. Clean the insulation and remove the residual charge on the ground. Check the insulation, closing his wire, and then connect the contacts to the device and read the resistance of the insulation. In some cases, you can use a voltmeter with a large internal resistance
You will need
• megger, voltmeter
Instruction
1
Disconnect tested object from the source of electric current. After cleaning the insulation from dirt ground the object in order to remove residual charge. Depending on the operating voltage of the device select equipment designed for 1000, or 2500 V. For testing of the device make sure when you cut the wires it shows infinity, and when briefly closed 0. For device use wires with a large resistance of the insulation, which is not less than 10 Mω. Ground current-carrying cables of the device, which will be measured.
2
Connect the terminals of the device to the conductive device cables or network and start to rotate the generator to produce a stable voltage. To achieve this, rotate the handle of the hand generator with a frequency of 2 revolutions per second. For some time the readings will increase, therefore, apply voltage for 1 minute when the readings stabiliziruemost.
3
To the readings of the megger is not influenced by the leakage current on the insulating surface, the device is connected with a special screening clip. Then this current is given directly into the ground, bypassing the device.
4
Please note that measurements need be made at a temperature not below +5 degrees Celsius. Unstable humidity at lower temperatures does not allow to obtain the true resistance reading of the insulation.
5
Working with a megger, be sure to use clamps with insulated handles. If the voltage on the device exceeds 1 kV, additionally wear insulating gloves. Do not touch when testing the live parts of the device.
6
In the study of the resistance of the insulation on the DC generators or batteries, use a voltmeter with an internal resistance 30-50 ohms. To do this, measure the voltage between the poles of the source, then between each of the poles and earth.
Note
The device M-416 is used to measure resistance of grounding (earthing devices) and soil resistivity. Its measurement range is 0.1 to 1000 (Ohm). The device is powered with 3 batteries in a voltage of 1.5 (In). About 100 measured points, approximately 1 to 7 points does not correspond to the contact resistance. Sometimes more.
In electrical installations with insulated neutral with voltage up to 1000 V resistance of the grounding device to be used as protective earthing, must satisfy the condition: R3yI3 < 50 V. the power generators and transformers 100 kVA and smaller grounding device can have a resistance not exceeding 10 Ohms (p. 1.7.104 PUE). For measuring of resistance of earthing creates an artificial circuit current flowing through the tested earthing.

Advice 6: How to measure the internal resistance of the battery

Any current source has a certain internal resistance. It is involved in limiting the current through the load along with the resistance of the load. In order to get it, will have to measure the voltage at the source under different loads, and then produce a simple calculation.
Instruction
1
Fully charge the battery.
2
Take two loads. Each of them must load the battery so current that it does not exceed the maximum permissible for him. One of the loads needs to consume current approximately 30 percent of the maximum allowable long-term (not short!) for the battery, and the other 70 percent of it. Very convenient to use low-voltage incandescent lamps. They should be designed for a voltage somewhat greater than the EMF of the battery (the voltage at its terminals at no load). If you use a powerful lamp, secured in such a manner that it cannot be contact with any body parts and any flammable objects.
3
Connect the battery to the first load through the ammeter and in parallel to the battery, attach the voltmeter. Both devices connect to the correct polarity. Wait for transients lasting several seconds. Measure the current through the load and voltage of the battery. Write them down.
4
Disassemble the chain, then similarly connect to the battery instead of the first second load. Also record the results. In both cases, the measurements were performed quickly (excluding the time required for the completion of transient processes) to battery turned.
5
If the measurements are not expressed in SI units (e.g., the battery is thin and the currents through the load is expressed in milliamperes), translate them into this system.
6
Subtract the first voltage from the second and the second current from the first. The result of the first subtraction divide by the result of the second subtraction. Get the internal resistance of the battery, expressed in ohms.
7
Note that the internal resistance of the battery increases as the discharge and wear. Specially to wear it, perhaps not. But one cycle of the discharge (to a voltage slightly higher than the minimum safe for him) pass. At several points in this cycle, momentarily disconnecting the battery from the main discharge circuit, measure its internal resistance using the above method. Make a curve of internal resistance to the degree of discharge, expressed in percentage.
Note
Never exceed the maximum allowed discharge current of the battery, the more short it's short.
Search