Anti-pulse/Anti-surge resistors

Resistors that tolerate against pulse or surge are required to be used such as; precharge resistors in the circuit where large current is instantaneously applied or, resistors in the circuit where ESD is more likely to be applied. Pulse means the overload of large power and with long duration(large energy) whereas surge means overload like ESD, of high voltage and with short duration.

Anti-pulse resistors are unlikely to be damaged even if large power is instantaneously applied. Among SMD type resistors, thick film chip resistors(metal glaze film type) are generally stronger against pulse than metal film chip resistors. Thick film chip resistors with special construction like SG73, or SG73P are strong against pulse or surge. Metal plate chip resistors for current sensing apply metal plate for resistive body. This achieves the strong resistance against pulse or surge. Leaded type resistors, on the other hand, wirewound type resistors that wounds metal resistive wire around the insulator such as CW, CW-H,RW, BGR, BWR, are stronger against pulse than film type metal film resistors or carbon film resistors that have metal resistive film formed on the top of insulator. Solid type ceramics resistors that applies ceramics resistive body, are extremely strong against pulse. 

Anti-surge resistor means a resistor strong against instantaneous high voltage like ESD. SG73S ensures the ESD limiting voltage.

Pulse Resistance Level by resistor type(image)