Custom Search
|
|
|
||
 MIL-HDBK-419A
high depending on the value of the SCR current-limiting resistor. Because of the proliferation of solid-state
arresters available, it is strongly recommended that complete laboratory demonstration testing be required
prior to implementation of the solid-state arresters.
TURN ON
MAXIMUM CLAMP VOLTAGE
@ RATED PEAK PULSE CURRENT
TIME
TYPICAL OPERATING CURVE FOR SILICON AVALANCHE SUPPRESSOR
a.
MAXIMUM CLAMP VOLTAGE
@ RATED WITHSTANDING
SURGE CURRENT
TURN ON
TIME
TYPICAL OPERATING CURVE FOR ZNR SUPPRESSOR
b.
Figure 1-39. Typical Arrester Operating Curves, ZNR and SAS
d.
Hybrid type arresters. Hybrid type arresters are currently in development that consist of a
combination of gas-filled spark gaps and ZNR or MOV, and two-stage arresters consisting of a solid-state stage
for dissipation of low-energy-content transients and a separate stage for dissipation of high-energy transients
consisting of gas-filled spark gaps and ZNR or MOV. The two stages are separated by a very low dc resistance
choke so that the low-energy dissipation stage fires first to achieve fast response time. When sufficient voltage
develops across the choke, the high energy dissipation stage turns on and dissipates the high level transient
energy. Insufficient data currently exists to support analyzing the hybrid type arresters. A hybrid should
emerge that effectively utilizes the best characteristics of available devices, (e.g., the fast turn-on and low
clamping voltage characteristics of silicon avalanche diode suppressors and the high current dissipation
capability of ZNR or MOV and gas-filled spark gaps).
1-72
|
 
|
|
|
||
