DC resistance test principle

Saya Electric is a professional R&D and manufacturing DC resistance tester. The DC resistance tester produced by the company is widely acclaimed in the industry and strives to create the most authoritative "DC resistance tester" high voltage equipment supplier.
The DC resistance tester of the transformer winding is an indispensable test item after the transformer is overhauled, overhauled and the tap changer changed. By measuring the DC resistance of the transformer windings, it is possible to check the quality of the welding or connection of the leads, whether there is a short circuit or open circuit between the windings, and whether the tap-changer contacts are in good condition.
The DC resistance of a transformer is a must-test item in the manufacture of semi-finished products and finished products in the manufacture of transformers, installation, overhaul, change of tap changer, hand-over test, and preventive testing of the power sector. It is possible to check the welding quality of winding joints and whether or not there is a short circuit in the windings. It is possible to check whether the contact of the voltage tap switch is in good position and whether the actual position of the tap changer corresponds to the indicated position. If there is a break in the lead wire, multiple wires are wound around Whether there is a stock break or other circumstances. In order to meet the need for rapid measurement of DC resistance of transformers, our company developed ZZC-1A DC resistance tester. The instrument uses a new power supply technology, featuring small size, light weight, large output current, good repeatability, strong anti-interference ability, and perfect protection functions. The whole machine is controlled by a high-speed single-chip microcomputer and has a high degree of automation. It has automatic discharge and discharge alarm functions. The instrument has high test accuracy, easy operation, and can realize fast measurement of transformer's direct resistance.
DC resistance tester is a new generation DC resistance tester for transformers. It can automatically select the test current according to different types of power transformers and display the test results at the fastest speed. The DC resistance tester has the functions of charge and discharge indication, and the adoption of the liquid crystal display makes the instrument have a good man-machine interface and is the preferred device in the DC resistance test work. DC resistance tester is a high-precision replacement product that replaces DC single and double-arm bridges. The instrument adopts advanced switching power supply technology, and its measurement speed is more than 100 times faster than the bridge. The display part is measured by four and a half LCD liquid crystal display. The three and a half LCD liquid crystal display ambient temperature or test current value, overcoming other similar The product has the disadvantage of inconvenient reading of the displayed value in sunlight, and it also has an automatic arc suppression function. 3A DC resistance rapid tester has the advantages of fast speed, high accuracy, intuitive display, strong anti-interference ability, small size, low power consumption, stable and reliable test data, and free from human factors. The instrument has a built-in rechargeable battery pack (12V) for both AC and DC purposes for on-site and field testing.
DC Resistance Tester Application DC ground resistance tester is ideal for measuring DC resistance of various inductive loads such as power transformers, large motors, and transformers, as well as contact resistance of low-voltage switches, wire and cable, or interface resistance of welds.
Precautions
1. Be sure to reset the unloaded voltage regulator transformer before tapping. After the discharge is completed, the alarm sound stops for more than 10 seconds before the tap point can be switched.
2. Before disconnecting the wire, be sure to wait for the discharge to end before the alarm sounds. It is best to wait 10 seconds before removing the wire to ensure that the charge is fully discharged.
3. When selecting the current, refer to the range in the technical indicator column. Do not exceed the range and underrange. During over-range operation, the instrument is in a "charging" state because the current does not reach the preset value. When the range is undershot, “current is too small” is displayed. When these two states occur, the range should be confirmed and the appropriate current should be selected for testing.
4. Pay attention to the range when using the magnetic assist method. Because the high-voltage coils are connected in parallel and in series, 1.5 times the high-voltage coil resistance is added to the entire test circuit. If the over-range output current cannot be used to reach the set value or the output current is unstable.
5. When the short contact of the three lines of the auxiliary magnetic method is disconnected after discharging, there may be residual current, which may cause fire discharge when dismantled. This is a normal phenomenon.
6. When connecting the test clip to the leading end of the transformer winding, pay attention to that the lead end is exposed to air for a long time, and the surface of the lead end is covered with an oxide film, which may cause unstable or inaccurate measurement results, so when wiring Care should be taken to clean the oxide film, or after the test clip is connected to the lead-out terminal, twist the test clip a few times to scratch the oxide film to ensure good connection.
Since its inception, Yangzhou Soya Electric Co., Ltd. has introduced a number of high-level researchers and technical application talents, focusing on the development of new products and the introduction of high-tech, and has exchanged and cooperated with many famous universities and research institutes in Wuhan. So far independent research and development of the product series are: series resonance series, insulation test series, grounding test series, transformer test series, circuit breaker test series, transformer test series, high voltage test series, lightning protection test series, phase test series. The frequency conversion series resonance tester, breaker tester, DC resistance tester, switch tester, relay protection device, cable fault tester, insulation resistance tester, transformer tester, zinc oxide arrester characteristic tester and transformer Volt-ampere change ratio polar tester and other electrical test equipments have been widely used in electric power, petroleum, metallurgy, mining, water conservancy, railway, iron and steel, and chemical industries for a long time, and have been well received by customers.

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