How to Use a Megohmmeter

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A megohmmeter, also known as an insulation resistance tester, is an instrument used to measure insulation resistance. The following are the usage methods of a megohmmeter:

### I. Preparations before Use
1. **Check the Appearance**
- First, check whether the appearance of the megohmmeter is intact. Examine whether the dial glass is damaged, whether the pointer can rotate flexibly, and also check whether the terminal blocks of the megohmmeter are damaged or loose. If there are problems with the appearance, it may affect the accuracy of the measurement and may even cause damage to the instrument.
2. **Place Horizontally**
- Place the megohmmeter on a stable horizontal surface. This is because there are mechanical components inside the megohmmeter, such as the generator and the pointer mechanism. If it is not placed stably, the internal components may shake during the shaking process, affecting the accuracy of the measurement results. At the same time, it may also damage the instrument.
3. **Open - Circuit and Short - Circuit Tests**
- When conducting an open - circuit test, open the "L" (line) terminal and the "E" (earth) terminal of the megohmmeter, that is, do not connect any object under test. Then, shake the handle of the megohmmeter at a speed of approximately 120 revolutions per minute. At this time, the pointer on the dial should point to the infinity (∞) position. This is because, in an open - circuit state, the insulation resistance is theoretically infinite.
- When conducting a short - circuit test, short - circuit the "L" terminal and the "E" terminal. Similarly, shake the handle at a speed of about 120 revolutions per minute. At this time, the pointer should point to the "0" position. These two steps of testing are to check whether the megohmmeter itself is working properly. If the results of the open - circuit or short - circuit tests are not normal, then this megohmmeter may have a fault and needs to be repaired or calibrated before it can be used.

### II. Connect the Object under Test
1. **Clean the Object under Test**
- Before connecting the object under test, ensure that the surface of the device is clean and dry. Because if there are impurities such as dust, oil stains, or moisture on the surface of the device, it will affect the measurement results of the insulation resistance. For example, when measuring the insulation resistance of a motor winding, if there are oil stains on the surface of the winding, it may cause the measured insulation resistance value to be lower than the actual value.
2. **Connect the Wires Correctly**
- For most measurement situations, connect the "L" terminal of the megohmmeter to the conductor part of the object under test, such as the outgoing wires of the motor winding; connect the "E" terminal to the casing or the grounding part of the object under test. This connection method can measure the insulation resistance between the internal conductors of the device and the casing. When connecting, ensure that the connection is firm to avoid measurement errors caused by poor contact.

### III. Measurement Operations
1. **Shake the Handle at a Constant Speed**
- After connecting the object under test, start to shake the handle of the megohmmeter. The shaking speed should be uniform, generally maintained at about 120 revolutions per minute. This speed is relatively crucial because the reading of the megohmmeter is related to the shaking speed. If the shaking speed is too slow, the voltage output by the generator is insufficient, which will make the measured insulation resistance value higher than the actual value; if the shaking speed is too fast, it may damage the internal mechanical components of the megohmmeter, and it will also make the reading inaccurate.
2. **Read the Data**
- During the shaking process, observe the position of the pointer on the dial and read the insulation resistance value. The dial scale of some megohmmeters is uneven, so pay attention when reading the data. At the same time, in order to obtain accurate measurement results, the reading should be taken after the pointer stabilizes. Generally, the stable value of the pointer after one minute is taken as the measurement result. This is because when the shaking starts, due to factors such as the capacitance charging of the object under test, the pointer may swing to a certain extent and will only stabilize after a period of time.

### IV. Operations after Measurement
1. **Disconnect the Wires**
- After the measurement is completed, first stop shaking the handle, and then carefully remove the test wires connected to the object under test. When removing, pay attention to avoid the metal parts of the test wires from touching other parts of the device to prevent accidents such as short circuits.
2. **Organize the Instrument**
- Organize the test wires of the megohmmeter and place them properly in the storage position of the megohmmeter. At the same time, clean the megohmmeter to remove impurities such as dust on the surface, and then store the megohmmeter in a dry and safe place for future use. #tiktokrefugee#cat#tiktokban#china#抖音难民#EfficientWinding#PowerTransformers #TransformerManufacturing #ElectricalComponents #EngineeringExplained #transformador #eléctrico #tecnología #fábrica #foryou #viral #videocorto #manufactura #máquina #energía #shorts #tendencias #cableado #trabajofábrica #ingenieríaeléctrica #transformadordeenergía #transformadoreléctrico #fabricación #proceso #fabricante #procesodefabricación #EnvolturaAltaTensión #EEUU #Canadá #Australia #ReinoUnido #vlogdiario #diario #trabajoadistinta #Tesla #TrabajoDiario #cableeléctrico #ingenieríadeenergía #transformador #envolturaenfoil #naciónbajavoltage #ingenieríaeléctrica #EnvolturaBajavoltage #EnvolturaFoil #IngenieríaEléctrica