MULTIPLE-GRADIENT SURGE LIMITER Russian patent published in 2008 - IPC H01C7/12 

FIELD: protection of electrical networks and equipment against lightning and switching surges.

SUBSTANCE: proposed surge limiter incorporating stack of series-interconnected varistors has its stack assembled of varistors whose location through its height depends on Ev gradient that characterizes ratio of voltage across single resistor to its height; assumed as this voltage is either that across varistor carrying DC current of desired value or RMS value of voltage across varistor carrying AC current component of desired value, or voltage across varistor carrying pulsed current of desired amplitude and waveform; stack is assembled so that mean value of gradient Ev_{mean t} for group of varistors disposed at one third or half of stack height, as counted from its top end, is lower than mean value of Ev_{mean b} for group of varistors disposed below.

EFFECT: simplified mechanical design of limiter.

3 cl, 3 dwg