Precautions before and after the instrument is powered on

1. Learn how to use the instrument in detail

Carefully read the product manual of the instrument, and do not use the instrument without being familiar with it. Be familiar with the terminal wiring diagram on the back of the instrument, and the signal terminal and terminal of the instrument cannot be connected to the wrong position. The instrument must be well grounded. If the instrument terminal is not clearly marked, the available resistance scale can simply determine the signal input terminal and power terminal of the instrument. For most analog power instruments, since the analog power transformer is wound with copper enameled wire and has a certain resistance value (several ohms to hundreds of ohms), and the input signal terminal is connected to the internal input circuit of the instrument, generally speaking, the input resistance of the instrument is very large (more than tens of megohms). Therefore, when using a multimeter to measure the instrument terminals, the terminal with a certain resistance value is the power terminal of the instrument, and the terminal with a large resistance value is the input signal terminal of the instrument. However, for instruments with a certain resistance value, this method is not suitable because the input resistance of the switching power supply is very large.

2. Pay attention to the installation location of the instrument

Attention should also be paid to the installation location of the instrument. Do not place the instrument in a humid environment, where there is corrosive gas, or where there is strong vibration or electromagnetic interference.

3. Clarify the temperature model to which the instrument is connected

Check whether the temperature sensor connected to the instrument is suitable, whether it is a thermocouple or a thermal resistor, or the standard current signal (o-10ma, 4-20ma) transmitted by the temperature transmitter, whether the positive and negative poles of the signal are connected in reverse, etc. The power supply of domestic instruments is generally AC 220v, or DC 24v, and the power supply of foreign instruments is generally AC 110v. Be sure to clarify before the instrument is powered on. The power supply of the instrument is AC 110v. If an AC 220v voltage instrument is connected, the internal fuse will be burned out at the least, and the internal circuit of the instrument will be burned out at the worst.

4. Use of "setting-measurement" of position regulator

After the position regulator is powered on, turn the "Set-Measure" switch (or touch switch, dial switch) to the set position (the light-emitting tube starts to display at this time), turn the "Set Adjustment" knob or adjust the touch switch or dial switch to display the temperature to be controlled. Turn the "Set-Measurement" switch to the measurement position, and the number displayed on the instrument is the actual value of the measured temperature. Different types of position regulators have different working states, different contact opening and closing conditions, and different working states of the indicator lights when the actual value of the measured temperature is lower than or higher than the set value or between the upper and lower limit set values.