How to use a multimeter to measure power with a heating tube
The heating tube can be regarded as a pure resistive load, and the current flowing through the heating tube is pure active current. Use a clamp type multimeter with AC current measurement function to measure the current when the heating tube is working. The value obtained by multiplying the current value by the rated voltage of the heating tube is the power (watts) of the heating tube.
For example, if the rated voltage of an electric heating tube is 220 volts and the measured current is about 2 amperes, then the power of this heating tube is about 440 watts. If the rated voltage of the heating tube is 380 volts and the measured current is about 1 ampere, then the power of this heating tube is about 400 watts.
One issue to note here is the rated voltage of the heating tube. If a heating tube with a rated voltage of 220 volts is connected to a voltage of 380 volts, it will quickly burn out the heating wire due to excessive voltage. On the contrary, if a heating tube with a rated voltage of 380 volts is connected to a voltage of 220 volts, it will not reach the rated power due to not reaching the rated voltage.
In actual production, both 220V and 380V electric heating tubes are often used. When customizing electric heating tubes, it is best to have the manufacturer stamp the rated voltage on the heating tube shell. To avoid confusion.
Is a multimeter used to measure the quality of a threaded bulb?
If it's an ordinary old-fashioned incandescent lamp, just measure the resistance range of a multimeter, and both a pointer multimeter and numbers can be used. The digital meter uses a 2k Ω range, and the pointer meter uses an Rx1 or Rx10 range. Due to the cold resistance of the filament being measured at this time, the resistance value is within the range of tens to hundreds of Ω (the larger the wattage, the smaller the resistance value).
If measuring LED bulbs, it can only reflect whether their rectification and filtering parts are normal, and cannot 100% determine the overall quality of the bulb. It is best to use a pointer type multimeter to measure (sometimes the digital meter output voltage is too low to measure data).
Move the pointer to the Rx10K position to directly measure the two contacts of the light bulb. Due to the charging effect of the filter capacitor in the lamp, the pointer at this time is very similar to the state when measuring the capacitor. After swinging it for a while, gradually returning can be confirmed that the rectification and filtering part is normal. In addition, you can also turn on the light bulb and use the diode range of a digital meter or the Rx10K range of a pointer meter to measure the quality of the LED beads one by one. However, there is now a small integrated lamp bead with a higher forward conduction voltage, some even reaching up to 30V, which cannot be measured with any multimeter.
