CLAMPING CONTROL CIRCUIT FOR HYBRID SURGE PROTECTION DEVICES.

摘要

A hybrid surge protection device (SPD) having a clamping voltage that is controlled by precisely limiting the overshoot voltage of a gas discharge tube (GDT) in a hybrid suppression network. The suppression network is conventionally connected between a protected line carrying current from a power source to a load and a return connection. The network includes a main surge suppression varistor (VR1) connected in series with the GDT. A clamping control circuit in parallel with the network includes a voltage limiting device (VR2) in parallel with the GDT for preventing voltage overshoot by the GDT above a limiting voltage responsive to an occurrence on the protected line of a surge combination wave. The clamping control circuit also includes a capacitor (C1) connected in parallel with the VR1 providing a bypass path for electrical current and voltage potential to the GDT. Biasing resistors R1 and R2 can be connected in parallel to C1 and VR2, respectively, to distribute the voltage betwee n the clamping control circuit and the network.