Product introduction

The dry type AC DC high voltage testers are relative to traditional oil immersed test transformers. It uses epoxy resin casting or high-quality insulation material as the main insulation, which seals the high-voltage coil and iron core into a whole. This design gives it the advantages of being oil-free, fireproof, moisture-proof, maintenance free, small in size, light in weight, and easy to move, making it particularly suitable for use in situations that require high safety and portability, such as indoor use in substations, industrial and mining enterprises, and power maintenance sites.

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working principle

The input voltage of this series of products is 200V or 400V, which is connected to the matching control box (platform). The input voltage is adjusted by an autotransformer to the primary winding (low voltage) of the test transformer. Using the principle of electromagnetic induction, the secondary winding (high voltage) can obtain an output high voltage of the same multiple according to its ratio to the number of turns of the primary winding. It can be continuously adjusted from zero volts to the rated maximum value. When conducting DC withstand voltage and leakage current tests, simply rotate the high-voltage silicon stack onto the high-voltage output terminal to obtain DC high voltage, which is 1.414 times the amplitude of the power frequency high voltage value.

technical parameters

Impedance voltage	≤12%
Output voltage wave form	sinusoid
Surface temperature rise	＜55℃
No-load current	＜4%

Main product specifications

specifications and models	capacity(kVA)	input voltage(V)	output voltage(kV)	output current(mA)	Output DC high voltage	weight(kg)
1.5/50	1.5	200 or 400	50	30	70	15
5/15	5			333		15
3/50	3			60		20
5/50	5			100		27
6/50	6			120		30
10/30	10			333		30
10/50	10			200		40
15/50	15			300		50
20/50	20			400		55
25/50	25			500		60
30/50	30			600		65
15/25	15	220	25	600	200	72
5/100	5	200 or 400	100	50	140	60
10/100	10			100		65
10/120	10			120		70
15/100	15			150		75
20/100	20			200		75
25/100	25			250		80
15/120	15		120	125	/	120
20/120	20			160		130
25/120	25			200		140
30/120	30			250		150

Daily inspection and maintenance

1. In order to ensure the normal operation of the transformer, it is necessary to conduct regular inspections and maintenance. In dry and clean places, conduct an annual inspection, while in places where there may be dust or chemical smoke pollution, conduct an inspection every 3-6 months.
2. The maintenance and repair items during the operation of dry-type transformers should be determined by comprehensive analysis of various factors. During operation, the appearance should be inspected according to regulations to confirm that it is in normal operating condition. If any abnormalities are found, it should be promptly shut down and dealt with. The daily inspection items include:
(1) Check for any abnormalities in the operating status, current, voltage, load, frequency, power factor, etc. of the transformer.
(2) Is there any abnormality in the temperature of the transformer. This is an important item in daily inspection, and when measuring temperature, the accuracy of the measuring instrument itself must be ensured first.
(3) Are there any abnormalities in the fan and cooling system. In addition to confirming the sound of the fan and cooling device, it is also necessary to determine whether there is vibration and abnormal temperature.
(4) Lead connector. Determine whether the lead joint and cable busbar are overheated based on the color change of the temperature indicating coating and the paint.
(5) Check for overheating and abnormalities in the contacts of the on load tap changer.
(6) Transformer appearance. Is there any dirt or contamination attached to the transformer windings, iron cores, etc.
(7) Appearance of insulation components and windings. Whether there are carbonization and discharge marks on the surface of insulation parts and windings, and whether there are cracks.
(8) Voice. Is there any abnormal noise or vibration in the transformer and its accessories.
(9) Smell. When the temperature is high, whether the insulation is burnt or emits a foul odor.
(10) Shell inspection. Confirm if there are any foreign objects entering the shell, if there is rainwater dripping in, and if there is any other contamination. Is there any resonance sound inside the casing, and is there any discharge sound caused by poor grounding.
3. During inspection, if excessive dust accumulation is found, it must be removed to ensure air circulation and prevent insulation breakdown. Pay special attention to cleaning the insulators of the transformer, the protrusions of the lower pads, and the surface of the high-voltage winding, and use dry compressed air (2-5 atmospheres) to blow away the dust in the ventilation duct.
4. Check whether the fasteners and insulation parts on the transformer body are loose, and whether the conductive components are rusted, corroded, or carbonized.
5. After several years of operation (generally recommended for 5 years), dry-type transformers need to undergo insulation resistance and DC resistance tests to determine whether the transformer can continue to operate.
6. After the dry-type transformer is put into operation, a power outage inspection should be conducted at regular intervals (at least once a year), and the inspection items are:
(1) Check for dust accumulation and rust in various parts of dry-type transformers.
(2) Temperature control, accuracy of temperature display values, recording the highest temperature that has ever occurred.
(3) Whether the joints and conductive parts are overheated or loose.
(4) Can the fan cooling device operate reliably according to the set value.
(5) Whether there is discoloration, delamination, or cracking in the insulation of each part.
(6) Check the grounding system of dry-type transformers: whether the grounding conductor is damaged or broken, and whether the connector is loose or damaged; Check point by point whether the entire grounding system is sturdy and reliable; Detect transformers and their distribution systems.