Electric hoist grounding system how to detect

      Detecting  Wire rope hoist  grounding system in two ways: The first is to measure the electric shake table testing, and the second is to use clamp-on resistance meter testing.
(1) Electricity shake table
Mainly used to measure electric hoist a point grounding resistance.
(2) Clamp resistance measuring instrument
The instrument will generate an AC voltage signal E, E is a known quantity, the coil current measurement instrument measured a current value, whereby the loop resistance of E / I. If the instrument displays <10Ω, you can determine where the grounding resistance (10Ω, if found instrument displays dozens Ω, then the need for further measurements judgment, but if the instrument displays the value is very high, it is necessary to check whether this ground is defective. If the TN-S system, with the vise jaws ground, it can be measured; if it is three-phase four-wire, grounding and repeated ground distribution system constitutes a loop. vise protective grounding wire can; if it is three-phase three-wire, Direct measurement of the ground wire is invalid because ungrounded power distribution device connected to the  rope hoist   therefore, by forming a loop. only measure the ground resistance of the grounding.