320 Watt Pulse Start 21UF 400 Volt (Dry Film)
Aerovox D84W4021M01H 21UF 400 Volt, 320 Watt Pulse Start Capacitor.
Commonly used for 320 Watt metal halide fixtures and works with M-132 bulbs with a constant wattage autotransformer circuit type ballast. The case is 1.77" diameter and 3.62" tall with a maximum temperature rating of 100oC (212oF). This case has two 8" long 18 gauge stranded copper wire leads with UL listed insulation rated for 150oC (302oF) and a resistor that dissipates charges to less than 50 Volts in 60 seconds when DE energized. This device is not protected against short circuit.
All Aerovox lighting capacitors have resistors, some resistors are internal and others are external.
Capacitors do deteriorate; stop replacing ballast kits if the transformer is good. The average life of an Aerovox capacitor is 60,000 hours, most other brands of capacitors only average 10,000 hours. They can become weak, this is easy to check. See the Meters Section or Video Section on homepage.