How to use a multimeter to measure whether a circuit is grounded using resistance step
Multimeter how to measure the circuit is grounded with the resistance file, first of all, regardless of the measurement of any line and equipment, we must first measure the voltage to ensure the safety of no voltage, and then other measurements, if the capacitance or capacitive resistance of the equipment but also the first discharge, and then to determine the safety of no voltage; and then will be adjusted to the 2000 megohm multimeter gear level, the meter pen one end of the contact grounding body or equipment metal casing, and the other pen contact with the equipment or the normal conductive body of the line charged, if the resistance is less than 0.5 megohm that is grounded. Line normal charged conductive body, if the resistance is less than 0.5 megohm that is grounded. Generally greater than 0.5 megohm 30 mA leakage protector will not trip protection so generally considered line or equipment is not grounded. But also depends on the equipment or line operating voltage or various technical requirements.
In daily life, as for the circuit range is very wide, I do not know which aspect of the circuit you are referring to, there are electronic circuits, electric money circuits to deliver voltage, electric motor circuits, etc., on the three commonly used circuits as an example of how to use a multimeter resistor block to measure whether the grounding.
First, electronic circuits, in general, the measurement of electronic circuits to choose the multimeter
Table stop for the maximum stop 10k stop, then the measured resistance is almost close to 10K, the pointer moves slightly, and then the pen to the measurement, some electrical appliances will be different after the pen to the difference will be a little less, because in electronic circuits, in order to resist high-frequency interference, equipped with high-frequency capacitors grounded, so the amount of a certain amount of value to the ground is normal. Thus, usually make people feel the phenomenon of numb hands, this circuit can not be measured with a shaking table, will damage electronic parts.
Second, the voltage delivery circuit, as an example, the household lighting circuit, before measuring the first to disconnect the power switch, but also to disconnect the switch of the appliances, and then measure the grounding situation, if the resistance of the circuit with a multimeter resistor block measurement of the resistance to ground, the resistance of the firewire-zero line should be infinity, the multimeter measurement of this circuit even if it is used in the 2 megohm block to measure, it is far from being enough because the multimeter within the laminated battery Voltage is only 9 volts, lighting voltage in 220 volts or so, if possible, it is best to use five hundred volts of megohmmeter (want to say shaking table), the measured resistance must be greater than 0, 5 megohm, in order to ensure that the circuit does not leakage.
Third, the motor circuit to the ground measurement, with a multimeter to measure is not, the same with five hundred volts of megohmmeter to measure the coil circuit to the ground resistance value is also greater than 05 megohms, to be considered safe, if it is a new winding of the motor coil to the ground resistance value must be greater than 10 megohms. So each circuit has different requirements for the resistance value of the ground, high voltage requirements for the ground insulation resistance value is large.
