The DC high voltage generator is suitable for the power department to perform DC high voltage testing on zinc oxide arresters, generators, transformers, switches and other equipment.
Operation method of DC high voltage generator:
(1) The test product is connected between the high voltage output terminal and the terminal.
(2) Plug in the power cord, turn on the power switch, the “High Voltage On” indicator (green) will be on, and the “High Voltage Off” indicator (red) will be on. will light up. be gone. Voltage display meter, current display meter and 0.75 times voltage display meter are all zero.
(3) Turn the voltage and current adjustment clockwise to the end, and turn the voltage adjustment counterclockwise shows up to zero. (Note: If the voltage adjustment knob is nott not in zero position, the "High Voltage Off" button cannot be activated.)
(4) Lightly press the "High Voltage" button, the "High Voltage" button The indicator light turns will light up (red) and slowly adjust the voltage. Adjust the knob to the voltage value required for the test. During the test, the voltage display meter displays the test voltage value in kilovolts. 0.75 times voltage display table 11 shows 75% of the test voltage value, the unit is kilovolt. Current display table 7 displays the test current value in kilovolts.
(5) If the 0.75 times voltage display lock button is pressed during sample testing, the display value of the 0.75 times voltage display meter is locked, making it inconvenient to maintain the display value, so the oxidized zinc arrester tested as the reference voltage.
(6) At any time, press the start buttontimer to start the time relay. When the time record reaches the predetermined time, the buzzer will alarm and cut off the high voltage output.
(7) During testing, if the load current exceeds 0-10% of the rated output current of the instrument. The “overcurrent” indicator lights up and the overcurrent protection prevents damage to the test and instrument.
(8) During testing, if the test voltage exceeds 0-10% of the rated output voltage of the instrument. The “overvoltage” indicator will illuminate and be overprotected to prevent damage to the test object and instrument.
(9) After testing, set the voltage adjustment knob counterclockwise to zero, and the voltage display will slowly return to zero. When all three display meters show zero, press the “High Voltage On” button. , "The “High Voltage Disabled” light (red) turns offnt, the “High Voltage On” indicator (green) lights up, then turn off the power switch.
(10) When the sample has a large capacity, the output voltage display counter cannot return to zero until the voltage adjustment knob reaches zero. Then use a discharge rod to discharge the test piece, and then remove the wiring from the test piece.
Respondent: Huatian Electric Power
Which model of megger is best for water-cooled generators?
Use a 500V or 1000V megger to measure, if the insulation resistance is 0.5MΩ or more, it is qualified.
A megger, also known as a megger, is an instrument used to measure the insulation resistance and high value resistance of equipment under test. It consists of a hand-cranked generator, a meter head and three. terminals (i.e. L: end of line, E: end of terre, G: shield end).
Before measuring, test the megger first. Open circuit and short circuit test, check if the megger is in good condition. If both connecting wires are open and the handle is shaken, the pointer should point to ∞ (infinity) at that time, if both connecting wires are short. -circuited momentarily, the pointer should point to 0. , at this moment, it means the oscillator is good.
Connect the L terminal (line end) of the megger to the water pump motor terminal box and connect the E terminal (ground end) of the megger to the water pump motor housing. water.
When measuring, press the meter housing with one hand (to prevent the meter from vibrating). When the needle indicates 0, stop shaking immediately to avoid burning the meter;
When measuring, place the meter in a horizontal position and turn the generator crank to a vispeed of approximately 120 revolutions per minute
The reading after the pointer is basically stable after shaking for about 1 minute, this is the insulation resistance value of the motor.
A megger, also known as a megger, is an instrument used to measure the insulation resistance and high value resistance of equipment under test. It consists of a hand-cranked generator, a meter head and three. terminals (i.e. L: line end, E: ground end, G: shield end).
Principles of selection of megohmmeters:
(1) Selection of the rated voltage level. Generally speaking, for equipment with a voltage rating below 500 V, a 500 V or 1000 V megger should be used; For equipment with a rated voltage above 500V, a 1000V~2500V megometer should be used. For equipment with a voltage rating greater than 10 KV, one megohm2500V meter should be used.
(2) Resistance range selection. There are two small black dots on the scale of the megger dial, and the area between the small black dots is the precise measurement area. Therefore, when selecting a table, the insulation resistance value of the equipment under test should be within the precise measurement area.
3. Precautions for using meggers
(1) The megger should be selected according to the voltage level of the equipment. For low voltage electrical equipment, a 500 volt. The megger must be selected. Using a megger with too high a voltage to measure low voltage insulation may cause insulation breakdown;
(2) Before measuring insulation resistance, the power supply of the equipment under test must be turned off. off and a short circuit discharge must be carried out. The purpose of the discharge is to ensure safetypeople and equipment and ensure accurate measurement results;
(3) The connection wires of the megger must be two separate. single wires (preferably two colors) with good insulation. Do not twist the wires together, and it is best not to contact the wires with the ground to avoid errors caused by poor wire insulation;
(4) Before measuring, carry out a open circuit and short circuit test on the megger, check if the megger is in good condition. If you open the two connecting wires and shake the handle, the pointer should point to ∞ (infinity). . At this time, if you short circuit the two connecting wires momentarily, the pointer should point to 0. At this time, it means
The megger is good, otherwise the megger will have errors;
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(5) When measuring, press the megger shell with one hand (to prevent the megger from vibrating). When Iguille indicates 0, stop shaking immediately to avoid burning the meter;
(6) When measuring, place the meter in a horizontal position and rotate the generator at a speed of about 120 revolutions per minute.Shake the handle;
(7) Before the megger stops rotating or the equipment under test is discharged, do not touch the measured part and the terminal of the instrument or remove Do not connect with your hands to avoid electric shock. ;
p>(8) If the weather is humid or the insulation resistance of the cable is measured, the shield terminal G (or protective ring) should be connected to eliminate the influence of leakage current on the surface. insulation;
(9) It is prohibited to use a megger to measure the insulation of equipment in lightning or humid weather and when there is high electrical equipment voltage nearby;
(10) Once the measurement is completed, the equipment tmust be unloaded.
4. The role of measuring insulation resistance and judging the resistance value:
Measuring the insulation resistance of electrical equipment is the simplest auxiliary method to check its condition insulation. The measured insulation resistance can detect defects such as foreign bodies affecting the insulation of the conductive part of electrical equipment, moisture and dirt in part or all of the insulation, serious deterioration of the insulating oil, breakdown of the insulation and significant thermal aging.
(1). The measured insulation resistance must be equal to or greater than the generally permitted value. The specific regulations of various electrical appliances are different: 0.5MΩ for low voltage equipment. 300 MΩ for 3-10 KV and 300 MΩ for 20-35 KV 400 MΩ, 63-220 KV corresponds to 800 MΩ and 500 KV corresponds to 3000 MΩ.
(2) Comparethe measured value with the value of the factory, shed and previous years. There should be no significant change from the previous test result, usually not less than 70% of the previous value. .
(3) The absorption rate of transformers of 35 kV and above should be measured, which is generally not less than 1.3. (Absorption rate calculation: insulation resistance measured in 60 seconds is better than insulation resistance measured in 15 seconds).
How many megaohms should a generator's insulation be normal?
Type ED2678 Water Cooled Generator Insulation Characteristics Tester
Main Features
Suitable for measuring insulation resistance, absorption ratio (R60s/R15s) and polarization index (R10min/R1min) of water-cooled generators.
The high test voltage is 2500V, and the insulation resistance can be measured up to10,000 megohms.
Automatically compensates and adjusts the polarization potential of water. The resistance between the machine base and the water collection pipe is as small as 3kΩ, which can also ensure the measurement accuracy.
When the output power is large and the water resistance is 80kΩ, the test high voltage drop is <10%.
The insulation resistance value is displayed by a pointer meter and a 3 1/2LCD digital meter.
The two scale lines have automatic range conversion, logarithmic scale and convenient reading.
Display output high voltage value and ambient temperature
LCD timer displays test time and displays minutes and seconds in a cycle of 0-32 minutes. The buzzer sounds every 15 seconds.
Press the [Rt] key, the LCD can instantly display the insulation current at the momenttuel.resistance value.
Can automatically measure and store R15, R60, R10min, absorption ratio (R60s/R15s) and polarization index (R10min/R1min). To review and read once the test is completed.
Comprehensive protection functions to ensure safe operation.
Reference materials are from: China Electric Power Test Equipment Network
Testing DC High Voltage Generator?
The insulation resistance of the generator should not be less than 0.5 MΩ.
Insulation resistance is the most basic insulation indicator for electrical equipment and electrical circuits. For transfer testing of low-voltage electrical equipment, the insulation resistance of motors, distribution equipment and distribution lines at normal temperature should not be less than 0.5MΩ (for equipment and lines in operation , insulation resistancent must not be less than 1 MΩ/kV).
As long as the insulation resistance of the generator rotor winding is not less than 0.5MΩ, it can be considered qualified.
The insulation resistance of the generator stator is not less than 1MΩ per kV and can be considered qualified.
Detailed information:
Since insulation resistance is greatly affected by temperature, insulation resistance will decrease by half for every 10°C increase in temperature. Therefore, for ease of comparison, the insulation resistance at different temperatures is usually converted into a value. insulation at 75°C.
Factors affecting insulation resistance
1. Ambient temperature and humidity:
The insulation resistance value of general materials decreases with increasing ambient temperature and humidity. Relatively speaking, surface resistance (rate) is more sensitive to ambient humidity, while volume resistance (rate) is more sensitive to temperature. Therefore, when measuring insulation resistance, it is necessary to specify the temperature and humidity at which the sample and the environment are in equilibrium.
2. Cable Specific Factors: When the cable is heated and wet, the insulation material ages. Its insulation resistance is reduced.
Baidu Encyclopedia - Generator Test
Baidu Encyclopedia - Insulation Resistance
1. DC withstand voltage and leakage test
In order to obtain good insulation, the leakage current under the action of the DC voltage is very low. As the DC voltage increases, the current flowing decreases. Under conditions of good insulation, as the applied DC voltage increases, the leakage current increases due to the rapid movement of ions. However, in the low voltage range, the leakage current has a linear relationship with the increase in applied voltage, and the increase range is very small.
2. Zinc Oxide Arrester Testing
The DC high voltage generator is specially equipped with a zinc oxide arrester testing function. This can increase the voltageAdd to the leakage current of 1mA and press the button 0.75 times. The instrument can automatically reduce the voltage to 0.75 times. At this time, the leakage current is 0.75 times the leakage current of zinc oxide mesure U1mA. This current can reflect the insulation state of the zinc oxide arrester.
3. Insulation Resistance Test
Insulation resistance is the most basic insulation indicator for electrical equipment and circuits. When a direct voltage is applied to a dielectric, the resistance corresponding to the leakage current flowing through the dielectric after a certain time is called insulation resistance.
When a high voltage DC generator is used to pressurize the material under test, the current on the material under test will not immediately reach a stable value, but will decrease. When pressurized, a relatively large charging current flows, followed by a relatively long and slowly decreasing absorption current, and finally a relatively stable conductive current is obtained. The higher the measured resistance, the longer it will take to reach equilibrium. Therefore, in order to read correctlyAlthough the resistance value measured during the measurement process, it should be read after the value is stable.
4. DC withstand voltage test of rubber and plastic cables
The voltage after testing is 3 times the rated voltage of the cable. Under the specified test voltage (the test voltage should be increased by 0.5 times the rated voltage of each level in sections, and the leakage current should be recorded for 1 minute in each section; Note: If the leakage current and voltage increase disproportionately, this must be analyzed and checked in time. Previously, the traditional wiring method was to use the high voltage megger method to check the withstand voltage. a DC high voltage generator One phase has a withstand voltage, one phase has a withstand voltage device, the other phase is grounded, and the three-phase resistance is three times p>.