About the measurement application of megometer
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About the measurement application of megometer

Posted Date: 2024-02-04

How to use a megometer to measure the quality of a three-phase motor

The megometer is a common measuring device that can be used to initially evaluate the quality of a three-phase motor. The following are the steps to use a megger to measure a three-phase motor:

1. Preparation: Make sure the megohmmeter is in working condition and connect the corresponding power supply. Check whether the power supply of the megometer and the electric meter part are connected correctly, and whether the electric meter is calibrated accurately.

2. Connect the motor: Correctly connect the three-phase motor to be measured to the megometer. Usually, the U, V, and W wires of the motor are connected to the corresponding contacts of the megger.

3. Activate the megometer: turn on the power switch of the megometer and select the corresponding measurement range. According to the rated voltage and current of the motor, select the voltage and current range of the megger so that it suits the rated value of the motor.

4. Measure voltage: record and observe the voltage value of each phase of the motor. The megometer usually displays the voltage values ​​of the three phases U, V, and W. Make sure these voltage values ​​are within the normal range and do not differ by more than plus or minus 10% of the rated voltage.

5. Measure current: The megometer can also measure the current value of each phase. Note that the current value on the megometer is usually the effective value, not the peak value. Record and observe the current value of each phase of the motor to ensure that it is within the normal range and does not exceed the rated current.

6. Observe the indication of the megohmmeter: The megohmmeter is usually equipped with an indicator light or a digital display to display the working status of the motor. Observe the changes on the indicator light or digital display. If there are any abnormalities or error indications, the motor may be faulty.

How to measure ground resistance with megger

Megometers are usually used to measure parameters such as voltage and current, rather than directly measuring ground resistance. The measurement of ground resistance usually requires the use of specialized ground resistance testing instruments, such as ground resistance testers.

Ground resistance testers usually have specialized functions and measurement circuits that can measure the resistance of a grounding system. The following are general ground resistance measurement steps:

1. Preparation: Make sure the ground resistance testing instrument is in working condition and connect the corresponding power supply. Check whether the power supply and meter part of the test instrument are connected correctly, and whether the meter is calibrated accurately.

2. Connect the test instrument: Connect the electrode of the test instrument to the ground system to be measured. Usually, one electrode is connected to the ground point and the other electrode is connected to a reliable ground point or the power neutral line.

3. Set up the test instrument: Set the appropriate test parameters and measurement range according to the instruction manual of the test instrument. This may involve selecting test frequency and measurement range, etc.

4. Make the measurement: Measure the ground resistance according to the instructions of the test instrument. Test instruments often provide instructions for applying a certain current to the ground system and measuring the voltage drop. Based on the measurement results, the measuring instrument calculates and displays the ground resistance value.

5. Record the measurement results: Record the measured ground resistance value and note whether it is within the acceptance standard range. Different regions and application fields may have different standard requirements, so please check the relevant standards or consult professionals to determine the qualified range of ground resistance.

How to use a megger to measure whether a line is short-circuited?

Megometers are usually used to measure parameters such as voltage and current, but have limited ability to directly measure whether a line is short-circuited. To measure whether there is a short circuit on the line, you can use the following steps:

1. Disconnect the power supply: First, make sure the power supply on the measurement line has been completely disconnected to ensure safety.

2. Visual inspection: Carefully check the appearance of the circuit to see if there is any obvious damage, wear, breakage, etc. Pay special attention to whether the insulation of the circuit is cracked or damp, and whether any conductive material is directly exposed.

3. Use measuring tools: You can use electrical equipment such as a multimeter or circuit tester to further measure whether the line is short-circuited.

a. Resistance measurement: Use the resistance measurement function of a multimeter between two nodes on the line to measure the resistance value. Normally, there should be a relatively high resistance value, not a value close to zero. If a very small resistance value is measured, it may indicate a short circuit.

b. Open circuit test: Use a circuit tester or circuit breaker tester to connect the device to the circuit. If the tester shows current flowing in the line, or if the circuit breaker tester sounds an alarm, it may mean there is a short in the line.

4. Segment inspection: If the location of the short circuit cannot be accurately detected, the line can be inspected in segments. Break or remove connections in the line section by section and measure each section using the method above to determine exactly where the short circuit is located.

Review Editor: Huang Fei


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