Digital multimeter for frequency measurement of the UPS power supply method
For UPS power supply. The stability of its output voltage is an important parameter, the output frequency is also very important. But not directly with a digital multimeter frequency block to measure, because its frequency block can withstand the voltage is very low. Only a few volts. This can be connected to the output of the UPS power supply 220V / 6V or 220V / 4V step-down transformer, the voltage is reduced, without changing the frequency of the power supply, and then the frequency block and the output of the transformer connected to the frequency can be measured out of the UPS power supply.
In general, the use of digital multimeter or to use the correct method of operation, can not understand the principle and function to blindly use, reasonable in accordance with the correct method of operation is also conducive to the digital multimeter better for us to use, to extend the life of the instrument.
Frequency is the number of cycles a signal completes per second. Some digital multimeter can be measured, such as the FT215 digital multimeter by calculating the number of times per second the measured signal and trigger level intersection to measure the frequency of a signal. The trigger level for all ranges is the same as the COM terminal level. Under the AC measurement function, press SHIFT to start and close the frequency measurement function. Frequency measurement applies to AC only. During frequency measurement, the analogue pointer display and range display indicate the current AC voltage or current. Use the manual range function to incrementally select a lower range for stable readings.
Precautions for Multimeter Measurement Accuracy
(1) Keep your eyes perpendicular to the pointer when reading.
(2) Place the multimeter horizontally and adjust the mechanical zero before measurement.
(3) When measuring the resistance, every time you change the block, you have to adjust the zero. Replace the battery with a new one when it is not zeroed; (4) When measuring RC circuits, replace the battery with a new one.
(4) When measuring the resistance in the RC circuit, cut off the power supply in the circuit and drain the capacitor's stored electricity before measuring. After eliminating the human error in the reading, we analyse other errors; (5) When measuring resistance or high voltage, we should replace the battery.
(5) Measurement of resistance or high voltage, you can not pinch the metal part of the pen with your hand, so as not to shunt the human body resistance, increasing the measurement error or electric shock.
