2022 registered security engineer technology golden test point memorizes another 30 points, note the finishing point prediction , hold on to like + forward + review continue to update, click on my avatar on the Wendang version and send a private message to me: 2022
Insulation material Performance (key point)
(1) Electrical performance
(1) Electrical performance
The electrical performance of insulating material is mainly electricity. Obstacle. Rate. and. between. electricity. often. number. .
as an insulating structure, its main properties are insulation resistance , voltage resistance, leakage current and dielectric loss.
① resistivity : stable straight. flow. shape. state. The resistivity shown in the following materials.
② Dielectric constant: The larger the dielectric constant, the slower the polarization process.
③ Insulation resistance: the resistance encountered by leakage current, DC resistance.
(2) Mechanical properties
(3) Thermal properties
Heat resistance: used to measure the allowable working temperature of the insulating material.
arc resistance: Inorganic insulating materials have better arc resistance than organic insulating materials.
① The advantages of this distribution network are that it has better overvoltage protection performance, the risk of single-phase electric shock when grounding in one phase is less, and the fault grounding point is easier to detect.
② When a single-phase electric shock occurs in a grounded distribution network, the voltage that the human body bears is close to the phase voltage. In the grounded distribution network, the risk of a single-phase electric shock is greater than that of an ungrounded distribution network.
③ Since RE and RN are on the same order of magnitude (ohm level), it is missing. electricity. set up. Prepare. right. land. electricity. Pressure. one. Normal. No. able. drop. Low. arrive. install. Complete. Fan. Surrounding. by. Inside. .
④ The TT system should be equipped with a residual current protection device that automatically cuts off leakage faults. The TT system is only considered when other measures to prevent from indirect contact with electric shock to are difficult.
⑤ The TT system is mainly used for low-voltage users, that is, small users who have not assembled distribution transformer and directly introduce low-voltage power from outside.
