How does an insulated shake meter work?

When the meter is measured, the generator in the hand-cranked meter emits a corresponding more constant voltage and adds it to a terminal and the grounding end of the component under test, and the ground resistance value of the electrical appliance can be measured according to the size of the leakage current generated, that is, the insulation resistance value. According to the different measured voltages, the shake meter is divided into different specifications and models such as 250V, 500V, 1000V, etc. It is to measure the leakage current of the insulating material at a relatively high voltage.

The principle is the same as that of a multimeter to measure resistance. When the meter is shaken, the generator in the hand-cranked meter emits the corresponding DC voltage and adds it to the electrical appliance. According to the withstand voltage value of the material to be measured, the measurement voltage of the shake meter is divided into 250V, 500V, 1000V, etc., the higher the voltage, the higher the value of the insulation resistance can be measured more accurately.

The structure of the megohmmeter is mainly composed of two parts, one part is a hand-cranked DC generator, and the other part is a magnetoelectric ratio measuring mechanism. The generator is cranked by hand to reach the rated speed, and the voltage emitted by the generator is added to the movable coil of the instrument and the resistor to be measured. Before measuring, the megohmmeter should be checked once, the meter should be squared, shake the handle before wiring, the pointer should point at the "infinity", and then the terminal terminal should be shorted instantaneously, slowly shake the handle, and the pointer should be pointed at the "0", otherwise the megohmmeter is faulty and needs to be repaired.

When wiring, the "ground" E end should be connected to the equipment housing or ground wire, and the "wire" L end should be connected to the conductor to be measured. When measuring the insulation resistance of a cable, the "shield terminal" G should be connected to the insulation layer. <>

The method is as follows: 1. Before use, the side of the shake table should be placed away from the magnetic field, and placed on the horizontal plane, not too tilted.

2. Fix the measuring wire of the shake meter to the two binding posts of the shake meter, and the two measuring wires are not divided into positive and negative, and then tighten the screws.

3. Clamp one measuring wire to the motor winding, and the other measuring wire to clamp the shell of the motor.

4. At this time, start to rotate the shake handle, about 120 revolutions per minute, and the reading core touches the rubber after the shake is stable.

5. Each pair of windings of the motor needs to be measured according to this method, if there is a group that does not meet the standard, the motor can not be used.

Precautions for use:

1. It cannot be used with electricity, and the electricity should be checked before measurement, and the insulation should be measured where the electricity is tested.

2. At the end of the measurement, the large capacitance equipment should be discharged.

3. Not all equipment can be measured when the equipment is powered off, such as frequency converters.

4. The table lines should not be twisted together, but should be separated.

5. During the shaking test, no one can work on the device under test.

6. It is forbidden to measure the insulation resistance during lightning or near high-voltage equipment, and can only be measured when the equipment is not charged and there is no induced electricity.

7. It is strictly forbidden to touch the watch by hand before it stops rotating or before the equipment under test is discharged. When removing the sutures, do not touch the metal part of the lead wire.

(1) First of all, choose a shake meter that is suitable for the voltage level of the tested element, and for 500V and below lines or electrical equipment, a 500V or 1000V shake meter should be used. For lines or electrical equipment above 500V, 1000V or 2500V shake differential liquid should be used. (2) When testing the insulation of high-voltage equipment with a shake meter, it should be carried out by two people.

3) Before measuring the bridge, the power supply of the tested line or electrical equipment must be disconnected, that is, it is not allowed to measure the insulation resistance with electricity. And it is necessary to find out that the line or electrical equipment is unmanned before it can be carried out. (4) The meter wire used for the table must be an insulated wire, and it is not suitable to use a double-strand stranded insulated wire, and the end of the meter wire should have an insulating sheath; The line terminal "L" of the shake meter should be connected to the measured phase of the equipment, the ground terminal "E" should be connected to the non-measured phase of the equipment shell and the equipment, and the shield terminal "G" should be connected to the protective ring or the cable insulation sheath to reduce the error caused by the leakage current on the insulating surface to the measurement.

5) Before measuring, the shake meter should be checked by open circuit. When the "L" end and the "E" end of the shake table are not loaded, the pointer of the shake table should point to the "" When the L" end of the shake table is shorted with the "E" end, the pointer of the shake table should point to "0". Indicates that the shake table functions well and can be used.

6) The tested line or electrical equipment must be grounded and discharged before the test. When testing the line, you must obtain the permission of the other party before proceeding. (7) When measuring, the speed of shaking the handle of the shaker should be uniform for 120r min; After maintaining a stable speed for 1 min, take a reading to avoid the influence of the absorbed current.

8) Do not touch both wires at the same time during the allergy test. (9) After the test, the stitches should be removed first, and then the shaking table should be stopped. In order to prevent the electrical equipment from recharging the shake meter and causing damage to the shake meter.

The working principle of the shake watch: its magnetoelectric meter head has two movable coils at a certain angle to each other, which are installed outside a notched cylindrical core, and are fixed on a rotating shaft together with the pointer, forming the movable part of the meter head, which is placed in a permanent magnet, and the air gap between the pole of the magnet and the iron core is uneven. Since the hands do not have a damping spring, they can stay in any position when the meter is not in use.

The shake meter is composed of a hand-cranked generator, a vote and three binding posts (i.e., L: line end, E: grounding end, G: shield end), which is widely used in coal mine installation and maintenance, and is suitable for checking the insulation of motors, electrical appliances and lines and measuring high-value resistance.

1 10 Connect the power plug of the instrument to AC220V. Press the power switch to the ON position, preheat for 10 minutes, and the test can be normal.

Select the appropriate test voltage (500V).

Determine whether the "test" light is off, make sure that the binding post is not charged, connect the test piece, press the "test" button, and the instrument can charge the test piece and measure.

After the test is completed, press the "RESET" button or the test time is until the instrument automatically resets, and then the test specimen can be removed.

Repeat the above steps for the next measurement.

This tester can be used after the power is turned on, but in order to ensure accuracy, please warm up for more than 10 minutes.

7 10 When connecting the object to be measured, it must be in the reset state, that is, when the test light is off, to prevent high-voltage electric shock.

When measuring more than 100m, it is best to shield the measuring line. When wiring, the grounding post on the front panel of the instrument should be connected to the housing or housing of the DUT.

Try to avoid measuring too small a resistor, or shorting the two test clips.

Earth Resistance Tester Instruction Manual (I=10a,

The instrument is equipped with a pair (two groups) of test wires, red thick wire to red current binding post, red thin wire to red resistance binding post, black thick wire to black current binding post, black thin wire to black resistance binding post.

1. Adopt 2500V shake meter. Check that the shake table 0 digit and infinity indication are good.

2. Measure the insulation resistance of the high-voltage winding to the low-voltage winding and the ground, and connect the three-phase short-circuit of the high-voltage winding to the L end of the shake meter. The three-phase short circuit of the low-voltage winding is connected to the E end of the shake meter after grounding. According to the 120 revolutions per minute shake gauge, the resistance r15 is read at 15 seconds, and the resistance r60 is read at 60 seconds, and the reading r60 in one minute is the insulation resistance.

R60 R15 is the absorption ratio.

3. Measure the insulation resistance of the low-voltage winding to the high-voltage winding and the ground according to the method of 2. At this time, the three-phase short circuit of the low-voltage winding is connected to L, and the high-voltage winding is connected to E after the short circuit is connected to the ground.

Shake the meter to measure the insulation resistance, many electricians are reluctant to teach, learn this method, and judge quickly.

Measurement of insulation resistance.

The megohmmeter is composed of a hand-cranked DC generator and a magnetoelectric flow meter, and the DC voltage of the hand-cranked DC generator is added to the measured object, and the measured leakage current is converted by the flow meter to display the insulation resistance value on the dial.

The following points should be taken into account when using a megohmmeter:

1) The speed of the megohmmeter should be from slow to fast, the speed should not be fast and slow, when it reaches 120r min, it should be stable, after the speed is stable, the hand on the dial can be stable, and the indication of the watch hand is the resistance value of the measured insulation resistance. It should be placed horizontally when in use.

2) According to the rated voltage of the measured object, choose a megohmmeter with different voltages.

3) The insulated wire used in the measurement should be a single multi-strand flexible wire, the measuring wire should not be kinked or lapped, and should be placed in the air, the connection with the end button should be tight and reliable, and the connection with the equipment should generally use a fish mouth clamp to avoid causing measurement errors.

4) Before the measurement, the equipment or line should be disconnected from the power supply, and the instrument circuit should be disconnected, and then discharged, for large transformers, large motors and other large inductance, capacitive equipment and lines should also be discharged after the measurement. The discharge time is generally 2 3min, and the discharge time should be extended for high-voltage equipment and lines.

5) Before using the megohmmeter, the megohmmeter should be verified, when the terminal is open, shake the megohmmeter, the pointer should be in the "one" position, the e and l should be shortened, slowly shake the megohmmeter, the pointer should be in the "0" position. When checking, the pointer should not wobble when it is in the "one" or "0" position.

6) During the measurement process, when the pointer points to the "0" position, it means that the measured insulation has been damaged, and the megohmmeter should be stopped to avoid burning out the megohmmeter due to short circuit. During the measurement, when the pointer is stable at a certain value, it can be read in a time of no more than 305, and the longest time shall not exceed lmin.

7) The equipment in use should usually be measured when it is just stopped, so that the measurement results can meet the insulation resistance at the operating temperature. It is forbidden to take measurements in the event of lightning or in the vicinity of equipment with high-voltage conductors. Measurements can only be made if the device is not charged and cannot be induced by other power sources.

In the insulating shake table, the torque in the opposite direction is generated on the two coils, and the positive needle of the table is deflected at a certain angle with the size of the resultant torque of the two torques, and this deflection angle is determined by the ratio of the two currents, so the potential difference is generated, so the electricity is generated.

When measuring the insulation resistance of a cable, the shielding layer of the cable should be connected to the G terminal in order to prevent the leakage current on the surface of the cable from affecting the measurement accuracy. The insulation of the measurement high closed flexible wire drawn from the binding post of the shake meter should be good, and an appropriate distance should be maintained between the two wires and between the wire and the ground, so as not to affect the measurement accuracy. When shaking the shaker, do not touch the binding post and the tested circuit of the shaker with your hands to prevent electric shock.

After shaking the table, the binding posts should not be short-circuited to avoid damage. After shaking the watch, don't wait a long time.

Shake meter, insulation resistance tester.

Also known as megohm watch, shake watch, Meg watch.

It is used to test the insulation resistance.

**Varies depending on the test voltage. The commonly used hand-cranked 500v is only 200-300 oceans.

The insulation resistance meter is mainly composed of three parts. The first is a DC high-voltage generator, which is used to generate a continuous flow of high voltage. The second is the measurement loop. The third is display.

1) DC high voltage generator.

To measure the insulation resistance, a high voltage must be applied at the measuring end, and this high voltage value is specified in the national standard of the insulation resistance table as 50V, 100V, 250V, 500V, 1000V, 2500V, 5000V...

There are generally three ways to generate DC high voltage. The first type of hand-cranked generator type. At present, about 80% of the megohmmeters produced in China are made by this method (shake meter name**).

The second is to step up the voltage through the mains transformer and rectify the DC high voltage. The method used in general mains megohmmeters. The third is to use transistor oscillation type or special pulse width modulation circuit to generate DC high voltage, which is generally used by battery type and mains insulation resistance meter.

2) Measuring loop.

In the shaking meter (megohmmeter) mentioned above, the measurement loop and the display part are combined into one. It is done with a flow ratio meter head, which consists of two coils with an angle of 60° (about left), one coil is at the voltage end and the other coil is stringed in the measurement loop. The deflection angle of the meter head pointer is determined by the current ratio in the two coils, different deflection angles represent different resistance values, the smaller the measurement resistance, the greater the coil current in the measurement loop, then the greater the angle of deflection of the pointer.

Another method is to use a linear ammeter as a measurement and display. Since the magnetic field in the coil is non-uniform, when the pointer is at infinity, the current coil is exactly at the place where the magnetic flux density is strongest, so although the measured resistance is large, the current flowing through the current coil is very small, and the deflection angle of the coil will be larger. When the resistance to be measured is small or is.

At 0, the current flowing through the current coil is larger, and the coil has been deflected to a place with less magnetic flux density, and the resulting deflection angle is not very large. In this way, a nonlinear correction is achieved. Generally, the resistance value display of the megohmmeter header needs to span several orders of magnitude.

However, when the linear current meter head is directly connected into the measurement loop, it is not possible to distinguish the scales at high resistance values, and it is necessary to add nonlinear components to the measurement loop in order to achieve nonlinear correction. In this way, a shunt effect is achieved at small resistance values. At high resistance, no shunt is generated, resulting in resistance values displayed by several orders of magnitude.

You don't have to do it with two people.

Clamp the measuring workpiece with the crocodile clip on the pen and shake the handle.