The usage method and precautions of measuring clamp gauges
Clamp type ammeters are divided into high and low voltage, used to directly measure the current in the circuit without disconnecting the circuit. The usage method is as follows:
(1) When using a high-voltage clamp meter, attention should be paid to the voltage level of the clamp ammeter. It is strictly prohibited to use a low-voltage clamp meter to measure the current of the high-voltage circuit. When using a high-voltage clamp meter for measurement, it should be operated by two people. Non duty personnel should also fill out the second type of work permit. When measuring, they should wear insulated gloves, stand on insulated pads, and not touch other equipment to prevent short circuits or grounding.
(2) When observing the timing of the watch, special attention should be paid to maintaining a safe distance between the head and the charged part. The distance between any part of the human body and the charged part should not be less than the entire length of the clamp watch.
(3) When measuring on a high-voltage circuit, it is prohibited to connect wires from a clamp ammeter to another meter for measurement. When measuring the current of each phase of high-voltage cables, the distance between cable heads should be at least 300mm, and the insulation should be good. It can only be carried out when it is considered convenient for measurement.
(4) When measuring the current of low-voltage fusible fuses or horizontally arranged low-voltage busbars, each phase of the fusible fuse or busbar should be protected and isolated with insulation materials before measurement to avoid causing phase to phase short circuits.
(5) It is strictly prohibited to measure when one phase of the cable is grounded. To prevent ground breakdown and explosion caused by low insulation level of cable heads, which may endanger personal safety.
(6) After the clamp ammeter measurement is completed, turn the switch to the range position to avoid accidental overcurrent during the next use; And should be stored indoors in a dry place.
2, Detect the working voltage at all levels. Detect the working voltage at each point and compare it with the normal value. Firstly, ensure the accuracy of the reference voltage. It is recommended to use a digital multimeter of the same model or similar for measurement and comparison.
3, Waveform analysis. Observe the voltage waveform, amplitude, period (frequency), etc. of each key point in the circuit using an electronic oscilloscope. For example, if the clock oscillator is on and the oscillation frequency is 40kHz. If the oscillator has no output, it indicates that the internal inverter of TSC7106 is damaged, or it may be due to an open circuit in external components. The waveform observed at pin {21} of TSC7106 should be a 50Hz square wave, otherwise it may be due to damage to the internal 200 divider.
4, Measure component parameters. For components within the fault range, online or offline measurements should be conducted, and parameter values should be analyzed. When measuring resistance online, the influence of the components connected in parallel with it should be considered.
5, Hidden fault elimination. Implicit faults refer to faults that appear and disappear from time to time, and the instruments are sometimes good or bad. This type of malfunction is quite complex, and common causes include solder joints being poorly soldered, loose, loose connectors, poor contact of the adapter switch, unstable component performance, and continuous breakage of leads. In addition, it also includes factors caused by external factors. If the ambient temperature is too high, humidity is too high, or there are intermittent strong interference signals nearby, etc.
