When the DC resistance tester arrives, make necessary checks. Before unpacking, make sure that the arrow mark on the outer package of the device faces up. Do not knock hard when unpacking the device to avoid damage. Unpack the equipment and keep the outer packaging and shock absorption items of the equipment, which is convenient for your future use in transportation and storage and plays a role in protecting the environment. Unpack the equipment and check the equipment and accessories according to the packing list. If you find any missing, please contact the manufacturer immediately.
In everyday use, for transportation and storage of dc resistance tester and equipment using two important links, when equipment to transport, it is recommended to use our company instrument packaging wooden box and damping materials, in order to avoid unnecessary damage in transit, do not use wooden cases in transit, do not allow the stack emissions, transport equipment, instrument panel should be facing up. In daily storage, attention should be paid to placing it in a dry, dust-free, ventilated and non-corrosive gas room. In the case of no wooden box packaging, stacking is not allowed to discharge. When storing, the panel should be upward, and moisture-proof items should be placed at the bottom of the equipment to prevent the equipment from being affected by moisture.
Before use, dc resistance tester should do enough preparation work, understand the key points should pay attention to in use. Read the product instructions carefully before using the DC resistance tester, and operate in strict accordance with the instructions to prevent accidents. Dc resistance tester operators should have the common sense of general electrical equipment or instruments, for its maintenance care and adjustment should also be carried out by professionals.
Dc resistance tester should avoid violent vibration, and should avoid rain, corrosive gas and other places to use. When the DC resistance tester is tested, it is necessary to turn off the power and remove the test line after the discharge alarm sound stops. During the test, do not move the test clip and power supply line, measure the no-load voltage regulator transformer, be sure to switch gear after the discharge indicator alarm tone stops. For the sensitive test object, it is not allowed to remove the test line before discharging the power, so as to avoid electric shock. During the test, when external AC220V is suddenly powered off, the instrument will automatically discharge. At this time, it is not allowed to remove the test line immediately, and the line can be removed after 5 minutes.
In the test of oil pressure tester, the extraction of oil sample is an important work. Different test environment, different process, insulating oil sample collection methods are also different. The container and sampling method used for sampling directly affect whether the actual quality of oil can be reflected.
1. Sampling should be carried out on dry and sunny days. The oil sample for pressure test should be controlled above 0.5kg, and the oil sample for simplified test should be controlled above 1kg. Sample containers are colorless glass bottles with 0.5 kg or 1 kg of wide-mouth sand glass stopper. Two to three vials were collected at a time for analysis and test. Label the sample and pay attention to the oil sample name, source, sampling date, sampler, weather conditions and other information.
2. Before using the sample container, please clean it with gasoline, soapy liquid or other solvent to remove oil, so that it is not alkaline, rinse with water, until the water used flows down the wall of the bottle evenly. Wash it several times with distilled water. The cleaned sample container is dried in an oven at 105 degrees Celsius. After cooling, close the cork. Do not open it before use. After collection, firmly wrap the glass stopper with clean paper and cloth to prevent dirt and moisture from fouling the bottle mouth.
3. Outdoor sampling should be carried out in sunny days or dry weather with low humidity, and the intrusion of garbage such as rain and snow should be strictly prevented during sampling. The oil in the oil storage equipment should normally stand for more than 8h before sampling. If sampling is done in a running transformer, there is no need to stand. Before and after sampling, clean or hairless fine cloth should be used to wipe the area around the sampling port clean. When collecting oil samples from the transformer in operation, discharge about 2kg of accumulated sewage from the bottom of the drain valve or sampling valve at the bottom of the tank, clean the drain port, and then collect oil samples.
4. When collecting the new oil supplemented from the transformer and the oil sample just filtered, please fully stand before collecting the oil sample. From no drain pipe (or throttle) small transformer sampling, can be inserted into the transformer when it does not work with glass tube, extract the bottom of the oil sample, can also replace the sampling using oil change method.
5. When extracting from the tank, open the barrel cover, insert the clean and dry glass tube into the oil, press the tube mouth with your thumb, loosen your thumb, put the oil into the tube, press the tube mouth with your big finger, lift the glass tube, rotate while oil in the tube, clean the sampling tube, circulate 2 times after use. When sampling in batch drums, samples shall be selected based on 5% of the total number of drums, but not less than 2 drums. To use small buckets or whole bottles for sampling, 2% of the total number of barrels (bottles) shall be sampled. When extracting oil samples, the site fire prevention regulations shall be strictly observed.
The oil cup and electrode of the oil pressure tester need to be kept clean and protected with a new method of adding transformer oil when stopped. After testing inferior oil, clean it with solvent gasoline or carbon tetrachloride and dry it before continuing to use. The oil cup and electrode should be checked once after one month of continuous use. Check whether there is any change in the distance between the electrodes. Use a magnifying glass to observe whether there is darkness on the electrode surface. If there is such phenomenon, adjust the distance and wipe the electrode with deerskin or silk cloth.
If it is prohibited for a long time, this should also be done before use. The test oil shall be temporarily placed in the test chamber without destroying the original storage seal, and the test shall be started after the oil is close to the mild room temperature. Before uncovering, gently shake the test oil to make the internal impurities uniform, but do not produce bubbles. Before the test, clean the oil cup with test oil 2-3 times. When filling the oil cup, please slowly flow down the inner wall of the oil cup to reduce bubbles. Do not touch the electrode, the inside of the oil cup or the oil during operation. After the test oil is filled, stand for 10-15 minutes before the booster test begins.
In the test, spark discharge voltage changes in four cases. Spark discharge voltage is particularly low. During the test, the values may be lower due to some external factor in the dirty zone on the electrode surface of the oil cup during or before filling the oil cup. In this case, take the average of 2 to 6 times. This is because the value of the 6 spark discharge voltage increases gradually, and the moisture of the oil product after spark discharge is improved for the oil sample which is not purified and is not treated adequately. 6 spark discharge voltage gradually decreased.
Generally speaking, due to appear in the cleaner test oil, the generation of free charged particles, bubbles, carbon chips have increased, resulting in damage to the insulation performance of the oil, in addition to the automatic oil tester without stirring in the continuous test for 6 times, carbon particles between the electrodes gradually increased, the spark discharge voltage gradually decreased. The value of the spark discharge voltage is the lower middle height at both ends. This is a normal phenomenon.
In addition, in the oil pressure test, the pressure value deviation may be larger. In the test using the preventive test method, if there is a large deviation between the value of one of the six tests and other values, it may lead to poor oil quality or uneven distribution of free carbon if the value is not calculated or the oil sample is tested again.
Transformer is the main part of electric energy transmission and the key equipment of power transmission and transformation system. Its running state directly affects the reliability of power system. Once the transformer is in operation, it will cause serious consequences to the power system. Therefore, it is necessary to use the transformer core grounding current tester to detect the current of the transformer core grounding on a regular basis to prevent the occurrence of faults.
The detection principle is: when the transformer is running with electricity, the current loop will not be formed in the core, so the grounding current is very small, generally within tens of mA; When multipoint earthing, short-circuit turn around core main magnetic flux are equivalent to the situation, grounding line current will increase obviously, and through the circulation size is determined by location and normal pick applaud the relative position of irfpa by transformer core earthing line measuring the size of the fuses in the current, which can effectively determine whether transformer core multipoint earthing phenomenon exists.
Detection data When the detection result of transformer core grounding current is greatly affected by the environment and detection method, the comprehensive comparison can be made through the previous test results, and the judgment can be made according to its changing trend. The transformer core allows a point of grounding, because the transformer is working or testing, its core and parts are in a strong electric field, because of the effect of electrostatic induction, so there will be some suspension potential on the transformer or other metal structure, resulting in the damage of its parts.
It can be seen that when the transformer is running or testing, its iron core and all the metal components should be reliably grounded. If the core is more than a little grounded, a loop is formed between the ground points, and a loop is formed as the main flux passes through this closed loop during transformer operation. This will lead to partial overheating of the transformer core, and in serious cases, it will not even burn, causing some power accidents.
1, transformer core grounding inspection in the removal of iron choke after taking 5 pieces, in the burr at the maximum measurement with micrometer measurement, shearing burr < 0.03mm; Long side deviation 0.15mm, short side deviation 0.03mm, width deviation 0.2mm, parallelism < 0.4mm, straightness < 0.5mm, Angle deviation 0.03.
2, to detect whether the end face of the iron core is uneven with the depth of the vernier caliper, ruler measurement of the difference between the two adjacent iron chips on the upper end face of the iron choke, should not be > 1.0mm, core column diameter sign 330 mm. Check the flatness between upper limbs of the two lower clamps. Use 3O0mm steel plate ruler and plug ruler to measure the outer side of phase A and C, and the flatness should be less than 3mm and the iron core diameter is 33Omm.
3, check the surface condition of the iron core to see the outer surface of the iron core should not be rust, but allow to be covered by the paint film rust, its area should not be greater than 20% of the visible part. The core lamination should not be wrong lamination, and overlapping edge pressing should not occur at the joints of each stage. Joint gap: when core diameter ≤ 330mm ≤ 1.5mm. Grounding check If the ground lug is connected, the iron core pair clamp and the gasket should be in the path, and the ground lug removed should be disconnected.
4. Check the appearance of the iron core. After the iron core is upright, the core column should not be obviously bent or deformed, and the inclination of the core should not be greater than 5 ‰ of the total height of the iron core. Iron core weight Check The weight of the iron core after stacking should be basically consistent with the drawing. If there is an agreement, the net weight should not exceed 0.5% of the weight specified in the drawing. After passing the no-load loss test, the new trial-produced product is allowed to deviate by + 30% compared with the standard.
5, inspection records Inspection personnel should fill in the above inspection results in the Core Testing Record. The judgment that examines a result and mark examine to outside appoint the iron core sampling that processes, above any unqualified all judge is unqualified to taste, should double spot check, examine to unqualified project 2 times still unqualified, judge this batch of products is unqualified to approve, should execute "unqualified product control program".
Dc resistance tester and multimeter and other instruments are the same as resistance measurement instruments. Both dc resistance and insulation resistance are based on Ohm's law. The only difference between them is the size of resistance measured. Although the theoretical basis of these resistance measuring instruments is the same, but why can't we use a multimeter to measure the DC resistance of electrical equipment such as transformers, so that dc resistance tester improves the measurement speed of test transformers, and has gradually replaced the original single-arm bridge. Of course, because the DC resistance tester is used in precision electronic components, resulting in the measurement of perceptual samples, need to be fully discharged before removing the wire, otherwise it may cause the feedback of large current impact and burn out the instrument. It may not be as bad as single-arm bridge and other traditional instruments, but there is no denying that the progress of science and technology is changing our way of production and life.
Dc resistance measuring instrument is a practical instrument for measuring dc resistance and low voltage switch contact resistance, cable wire or weld interface resistance of various rational loads such as power transformers, heavy motors and mutual inductors. Dc resistance rapid tester is a high-precision replacement of dc single and double - arm bridge. Dc resistance test of transformer winding is an essential test item after transformer handover, overhaul and change of tap switch. By measuring the DC resistance of the transformer winding, we can check the welding or connection quality of the lead wire, whether the winding is short or open between turns, and whether the contact of the tap switch is good. QJ44 double-arm bridge was used to measure the direct resistance in the past, and the measuring current of this kind of bridge is milliampere level, which takes a long time to measure, and the accuracy is low. In order to change this situation, shorten the measuring time and reduce the workload of the tester, the dc resistance rapid tester was developed.
In a generator, electric potential can be induced in the coil, whether the coil is moving through a magnetic field or whether the magnetic field is moving through a fixed coil. In both cases, the value of magnetic flux remains constant, but the amount of magnetic flux intersecting the coil changes, which is the principle of mutual inductance. A transformer is a device that uses electromagnetic mutual inductance to convert voltage, current and impedance.
Transformer capacity tester includes two aspects. One is hysteresis loss. When the ac current passes through the transformer, the direction and size of the magnetic field lines of the silicon steel plate passing through the transformer will change accordingly, so that the molecules inside the silicon steel plate rub against each other, releasing heat energy, and thus losing a part of the electric energy, known as hysteresis loss. The other is the eddy current loss during transformer operation. A magnetic field line runs through the core and an induced current will be generated in a plane perpendicular to the field line.
Because this current forms a circulating loop and an eddy current, it is called an eddy current. The presence of eddy current causes the core to heat up and consume energy. This loss is called eddy current loss. The efficiency of a transformer is closely related to its power level. In general, the higher the power, the smaller the ratio of loss to output power, the higher the efficiency. Conversely, the lower the power.
The instrument displays three-phase voltage, three-phase current, three-phase power, the instrument displays the distortion rate of the applied power waveform, automatically calculates the transformer's no-load current converted to the rated voltage and the no-load loss corrected by waveform distortion, and displays the type of oil-immersed or dry-type distribution transformer core.
Can be used to check transformer single-phase defects or used in the absence of three-phase power on site. The instrument can record three single phase measurement data, and can calculate the transformer no-load current, no-load loss, impedance voltage and load loss according to different transformer connection.
Instrument built-in rechargeable lithium battery, itself can output three-phase sine wave inverter power supply, automatically adjust the output voltage, with soft opening and soft stop function, without any external power supply which can realize the measurement of distribution transformer capacity and judgment of the model, at the same time shows the transformer impedance voltage and temperature conversion), rated power flow load loss.
Wireless temperature measurement system adopts the industry's wireless temperature sensor, microcomputer technology, wireless communication technology, electromagnetic compatibility design technology, ultra-low power design technology, reliable application in the cable joint online temperature measurement, And can be extended to power plants, distribution substation, factories and mining enterprises distribution substation room switch cabinet, transformers, circuit breakers, transformers, power capacitors and other power equipment online temperature monitoring.
This system can measure temperature wirelessly 24 hours a day without omission, and realize overtemperature alarm. By monitoring the temperature of the monitoring point in operation, the health files of the monitoring area are established. When there is an abnormal situation on site, alarm signals can be sent to inform relevant personnel to deal with it as soon as possible, so as to facilitate the purposeful arrangement of maintenance period and maintenance items, so as to effectively ensure the healthy and stable operation of the whole monitoring network.
System features: wireless temperature monitoring system has simple structure, easy wiring, convenient and quick construction; The temperature sensor is small in size and can be installed directly on the high voltage charged body, which is convenient to install in complex environment. The use of digital temperature core, high temperature measurement accuracy, temperature error is small, unlike the infrared temperature measurement by the environment, Angle. Through 2.4g high frequency communication to upload data, transmission distance can reach 300M, the power supply system without any interference.
The temperature sensor is designed with very low power consumption, which can ensure the service life of the product reaches more than 8 years. Data tap box can receive data information from 256 sensors; Data access box has a variety of interfaces, support a variety of communication modes; Software humanized design, alarm processing more reliable, more accurate alarm analysis.
System structure: it adopts object-oriented design and distributed system architecture, and consists of wireless temperature sensor, wireless temperature collector, communication gateway, transmission channel, server and so on. The wireless temperature sensor is directly installed on the temperature monitoring point, using high performance and high reliability battery power, and through the 2.4ghz wireless force message will be sent to the temperature data communication gateway, there is no direct contact with the communication gateway, so it will not affect the insulation of the equipment.
A server is set at the local end, which collects and summarizes data from several substations, substation and user stations through specific wired or wireless channels to realize real-time data display, historical data storage, report generation, historical curve, SMS alarm and other functions, and can be expanded according to the needs of users.
Baoding Excellence Electric Co., Ltd. to tell you about the transformer capacity tester in the measurement process must not touch the metal part of the test line, in order to avoid being injured by electricity.
1. Measuring wiring must be operated strictly according to the instructions, otherwise the consequences shall be borne by you.
2. Before testing, make sure that the parameters set are correct.
3. It is good to use electrical outlets with ground cables.
4. Cannot operate under voltage and current overlimits.
5. During the short circuit test, the short connection of the non-pressurized side must be good, otherwise it will affect the test result.
6. During the short circuit test, if the high voltage or medium voltage side outlet bushing is equipped with annular current transformer, the secondary current transformer must be short-circuited before the test.
7. The test wiring shall be carried out under the condition of grounding of the tested line to prevent electric shock by induced voltage. All short circuits, grounding and leads shall have sufficient cross sections and shall be securely connected. The test organization should be strict and the communication should be smooth to ensure the smooth progress of the test work.
8. When the instrument needs to charge, be sure to turn off the power supply (press "O" to turn it off), plug in the power cord, the yellow light of charging indicator starts flashing, indicating that charging is in normal state.
9. When testing transformers of 500kVA or 630kVA, it is necessary to set the reference capacity, because transformers of 500 and 630 are in the impedance voltage conversion zone, and the capacity may cross. In order to avoid misjudgment, this parameter must be set.
Wireless temperature measurement system consists of wireless temperature sensor, temperature measurement communication terminal (temperature receiver), temperature monitoring and early warning workstation.
1. Wireless temperature sensor: measure the temperature of the contact point. Mainly installed in easy to heat. Each wireless temperature sensor has an ID number. During actual installation and use, the installation location of each sensor is recorded and stored in the computer database of the temperature monitoring workstation with the number. The sensor automatically transmits the temperature data of the monitoring point at regular intervals (which can be set in advance). However, if the temperature is abnormal, the alarm will be sent immediately, and the transmission period is not limited.
2, wireless temperature receiver: installed in the substation station, according to the installation area installation, responsible for receiving the wireless temperature sensor (probe) measurement and sent temperature data, and through the bus connection, the temperature data uploaded to the management computer, response to the management software command.
3. Workstation system: wireless temperature measurement client software, real-time display of temperature data and change curve of monitoring points in each monitoring area, and query and analysis, once found that the temperature is overheated, or sharply rising to the set alarm temperature immediately alarm.
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