8
times the rated input current of the appliance, and the resistance value of the contact point is still
100mΩ, and the test time is 60 seconds. Most of these are electrical appliances, which are
dangerous, so the requirements for specifications are higher than general appliances.
In the current safety regulations in the world, some specifically require that the contact
resistance of the ground wire be measured first. The resistance of the contact must meet the
requirements before the insulation withstand voltage test can be performed. This is mainly to
prevent misconception that the insulation or voltage resistance is good because the ground wire
is not connected properly.
The ground resistance tester has two types of output: AC and DC. Both types can accurately
measure the resistance value of the contact point, but the two types have significantly different
destructive properties for bad contact points. Because the calculation of resistance value is the
effective value of voltage and current, and the effective value of DC is the same as the peak
value, but the peak value of AC is 1.414 times the effective value. Therefore, when AC is at the
peak, its current value is also 1.414 of DC Times. When comparing the energy generated by the
AC peak point to the contact point, the energy generated by the AC peak moment at the contact
point is twice the DC value when calculated according to the power theorem (power = current
squared X resistance).
Although the current security inspection agency allows two types of ground testers to be used,
AC ground resistance testers are particularly recommended in the selection of ground resistance
tester specifications. Secondly, most of the general appliances use mains power as the power
supply, and mains power is AC power, so the AC ground resistance tester is used as the test
standard, which fully meets the actual conditions of use.
If you have questions about the use of the instrument or problems related to the instrument,
please feel free to contact us.
