| 摘要 |
PCT No. PCT/GB89/01024 Sec. 371 Date Apr. 1, 1991 Sec. 102(e) Date Apr. 1, 1991 PCT Filed Sep. 1, 1989 PCT Pub. No. WO90/03058 PCT Pub. Date Mar. 22, 1990.An apparatus for protecting electrical installations against transients includes one or more devices comprising a network of varistors connected through a gas discharge tube to live, earth and neutral conductors. The varistors each have a terminal connected to an associated pole of the tube and the other terminal to the associated conductor. The apparatus may have three devices connected in cascade and preferably, inductances connected in series in the live and neutral conductors between the devices and the load. Preferably, varistors interconnect the conductors between the inductances and load. Relatively cheap and efficient apparatus for discharging transient over-voltages is provided. |
