Constant temperature and humidity test box maintenance experience sharing

The temperature and humidity test chamber is a very common environmental test equipment. Although its coverage rate is second only to the oven, and with the pursuit of perfection in the quality of equipment by customers, the actual operation of today's constant temperature and humidity test chambers is also relatively Convenient. However, whether it is cheap or expensive equipment, it is very complicated to maintain, which makes it impossible for users to repair and maintain equipment in time, and it is easy to accumulate faults and maintenance accidents are frequent.

The most common failure of the constant temperature and humidity test chamber is the humidity failure. There are many manuscripts on the Internet about the cause of the humidity failure, and they are very vague. Let me share with you the abnormal humidity faults of the constant temperature and humidity test chamber.

For example, after setting the temperature at 60 degrees and the humidity at 85% on the operating panel of the constant temperature and humidity test chamber, and operating the equipment with sufficient water in the water tank, the equipment can work normally after a period of time The temperature rises to 60 degrees, but the ambient humidity only shows about 3% or 5%, and the combined furnace is also very hot. The controller of the wet zone bulb is normal, and the instrument panel and solids can output normally. There is a lot of water in the cup, everything can be normal to power the heating furnace, overheat protection

The protective device has no alarm, the channel of the humidifier is measured with a digital multimeter, the thermistor is normal, and there is AC 220V voltage on both sides of the humidifier tube, but there is no steam coming out of the steam outlet of the furnace. This is due to the fact that water can produce electrical conductors under the special conditions that require purity to connect the originally burned out humidifier tubes to form a control loop, so this causes the humidifier tubes to be hot even though they are blown out The water in the heating furnace is boiled, but it cannot be boiled to form steam. In fact, the simple way to find this common fault is to use a clamp multimeter to accurately measure the current size of the humidifier tube when it is working. Under the known output power and working voltage of the humidifier tube, according to the accurate measurement Check the current and the calculated current. For example, the humidifier tube is AC220V, 2KW in size, and it can be calculated that the current is about 10A when it is working at full power. When the measured current is serious for less than an hour, it can be judged that the humidifier tube is blown out. Don't feel that the water in the furnace is hot, just think that the humidifier tube is normal, and look for other fault points.

Although the name of this fault is very simple, this type of fault is very rare, because when the humidifier tube or heating tube is short-circuited after being blown out, it has lost the ability to conduct electricity and will not cause heat generation Yes, so after some other substance modifies the conductor to connect it on and off except by accident, the humidifier tube restores part of the heating function.