Insulated Contact Box Parameters

Insulation Contact Box It is necessary to meet the insulation requirements of the corresponding voltage level of the product, such as the power frequency withstand voltage of 95kV for 1 minute and the lightning impulse withstand voltage of 185kV for the 40.5kV contact box. Therefore, the contact box needs to meet the requirements of clearance and creepage distance, and the wall thickness of the contact box needs to withstand the requirements of impulse withstand voltage. When the contact arm enters the contact box, although there is epoxy resin insulation between the contact arm and the mounting steel plate, if the air gap is too small, such as the epoxy thickness is 10mm, and the air gap is only 20mm, then according to the capacitance voltage division theory, the electric field strength of the air gap exceeds the normal value, which is easy to cause breakdown; at the same time, the effectiveness of the creepage distance must be ensured. If the material has a high tracking resistance index, the creepage distance can be reduced. The contact box needs to withstand short-time withstand current requirements, such as 31.5kA for 4 seconds and 80kA for peak withstand current. Therefore, the contact box should have a certain mechanical strength, such as bending resistance greater than 8kN.