How to measure the pros and cons of PTC heaters
The PTC heater manufacturer has checked that the power cord is not damaged, and the junction box is well sealed. Then use a megohmmeter (also called a shaker, insulation resistance meter) to measure the insulation resistance value of the lead wire of the electric heating tube or the lead rod and the tube of the electric heating tube (the ground wire of the electric heating tube is continuous with the tube of the electric heating tube), such as trillion The larger the guide value of Eurometer, the better, it means that the electric heating tube is well insulated, but the very low value should not be less than 2M ohm, otherwise the electric guard switch will trip and fail to work during application. .Use a multimeter resistance file (R*1 or R*10 file) to measure the lead wire or lead rod of the electric heating tube. There are two wires or lead rods for single-phase or two-phase, and the red and black test leads of the multimeter are used to test the lead wires. The guide value of resistance R is within the limits R=U*U/P, U refers to the marked voltage value of the electric heating tube, P refers to the marked power value of the electric heating tube), which means that the heating wire of the electric heating tube is not short-circuited.
The purchase should also pay attention to the anti-corrosion benefits of the material of the electric heating tube shell. The electric heating tube has been used for a long time. If the surface of the thick tube dirt and grease accumulates, it should be removed regularly, otherwise it will reduce the heat transfer performance and cause the heat load of the tube surface to exceed the rated value. Allowed and damaged. It should be stored in a dry stack. If the surface is damp due to permanent storage, a megger should be used to measure the insulation resistance.
In addition, we can also use a small resistance file to measure the wiring heads at both ends of the electric heater. The resistance should be less than hundreds of ohms. The resistance of the high-power electric heating tube will be smaller and the energy will flow, but the resistance value may be large. Burned out.
Then use the high-resistance file of the electric meter to measure the resistance between the connection pile head and the heating tube shell. If the resistance is only tens of kiloohms, the insulation of the electric heating tube may have been broken down, and there will be power failure during application. Dangerous, such a heating tube is very good, don't use it again.
Therefore, many people are eager to know how to determine the quality of the electric heating tube. Here I tell my friends that there is no inevitable standard for verifying the quality of the electric heating tube. It is determined by many ingredients. Today, let's take a look at how to verify the quality of the electric heating tube?
1. Material selection
The selection of materials for different heating environments is not similar:
1. Stainless steel 304 for normal water heating, stainless steel 316L for weak acid and weak alkaline liquids, and Teflon coating for strong acid and strong alkali.
2. Oil heating can be made of stainless steel 304 or iron.
3. Air heating is relatively special, it selects different materials according to the difference in temperature.
(1) Stainless steel 304 is used when the working temperature is below 300 degrees;
(2) Stainless steel 321 is used for air dry heating and electric heating when the working temperature is below 500 degrees;
(3) The working temperature of air dry heating and electric heating is below 800 degrees, using stainless steel 310S material;
2. Power design
Because the power design of the electric heating tube is different in different application environments, we usually measure it by the power per meter (that is, a one-meter-long heating zone can achieve a few watts of power).
(1) The power per meter of water heating is between 1-3;
(2) The power per meter of oil heating is between 1-2;
(3) The power per meter of air heating is between 1-1.5; beyond this limit, the greater the power, the shorter the life.
