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© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 (864) 963-6300 • www.kemet.com

A4031_ALS30_31 • 4/3/2014

Screw Terminal Aluminum Electrolytic Capacitors – ALS30/31 Series, +85°C

Mechanical Data

Polarity and Reversed Voltage

Aluminium Electrolytic capacitors manufactured for use in DC applications contain an anode foil and a cathode foil. As such, they are

polarized devices and must be connected with the +ve to the anode foil and the -ve to the cathode foil. If this were to be reversed then

the electrolytic process that took place in forming the oxide layer on the anode would be recreated in trying to form an oxide layer on

the cathode. In forming the cathode foil in this way, heat would be generated and gas given off within the capacitor, usually leading to

catastrophic failure.

The cathode foil already possesses a thin stabilized oxide layer. This thin oxide layer is equivalent to a forming voltage of approximately

2 V. As a result, the capacitor can withstand a voltage reversal of up to 2 V for short periods. Above this voltage, the formation process

will commence. Aluminium Electrolytic capacitors can also be manufactured for use in intermittent AC applications by using two anode

foils in place of one anode and one cathode.

Mounting Position

The capacitor can be mounted in any position as long as the safety vent can operate. It is possible for some electrolyte to be expelled.

As this is a conducting liquid, suitable precautions should be initiated by the system designer to avoid secondary short circuits.

The capacitors are designed to be mounted in free air and are not suitable for submersion in liquid.

Low Inductance Version

A low inductance version of the ALS30/31 capacitors can be designed upon request, typically reducing the inductance by up to 40% of

the standard capacitor's inductance. It is available in 77 & 90 mm diameters.

Insulating Resistance

≥ 100 MΩ at 100 VDC across insulating sleeve. UL recognized sleeving is available for custom parts in this range, upon request.

(UL No. E358957)

Voltage Proof

≥ 2,500 VDC across insulating sleeve

Safety Vent

A safety vent for overpressure is featured on terminal deck. This is in the form of a rubber plug designed to relieve build-up of internal

pressure due to overstress or catastrophic failure.

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• KEMET Logo

• Rated capacitance

• Capacitance tolerance

• Rated voltage

• Climatic Category

• Date of manufacture & Batch No.

• Article code