Leakage protector, also known as leakage switch, is a new type of electrical safety device, mainly used for: ZHEJIANG QIANNA ELECTRIC CO.,LTD , https://www.traner-elec.com
The V59 board screen shows T370HW V5. The initial fault was a grimace, followed by automatic shutdown. Then the green light turned red. The power board showed normal 5V and 12V, but 24V was missing. The 24V is supplied by an independent switch transformer. The IC used is UC3842, and its 15V power supply was normal. After some time, the 24V returned to normal. The test machine was still being screened, and after a few seconds, the screen turned gray as shown below:
Upon checking the logic board, the fuse F1 was open, and Q302 was also damaged (U801 power supply). A 12V maintenance power supply was added to the logic board, and the current reached up to 800mA. It was found that V20 and R205 were overheating. Although R205 had changed color, its resistance was still within normal range. After removing V20 and reapplying power, the current remained high. The hand touched U21 (AS15-G) and it felt hot. Replacing U21 resolved the issue. Then V20 was reinstalled, and Q302 was replaced with a 0-ohm resistor (welded at the R332 position, which was previously empty). The test machine worked properly after these repairs.
(1) Prevent electric shock accidents caused by electrical equipment and electrical circuit leakage;
(2) Preventing single-phase electric shock accidents during electricity use
(3) Timely cut off single-phase grounding faults in the operation of electrical equipment to prevent fire accidents caused by leakage
(4) With the improvement of people's living standards and the continuous increase of household appliances, personal electric shock and fire accidents caused by defects, improper use, and inadequate safety measures of electrical equipment in the process of using electricity have brought undue damage to people's lives and property. The emergence of leakage protectors provides reliable and effective technical means for preventing various accidents, timely cutting off power, and protecting equipment and personal safety.
The leakage protector should meet the following technical requirements
(1) The sensitivity of electric shock protection should be correct and reasonable, and the starting current should generally be within the range of 15-30 milliamperes
(2) The action time of electric shock protection should generally not exceed 0.1 seconds
(3) The protector should be equipped with necessary monitoring equipment to prevent it from losing its protective effect when the operating state changes. For example, for voltage type electric shock protectors, a neutral grounding device should be installed.