Capacitor Boots – The Case for Protection

Though often overshadowed by their distant cousin the battery, capacitors are a vital part of modern-day technologies. You’ll not only find them in computer chipboards but also HVAC units and around 20% of industrial electronics. A particularly versatile device, they’re not only capable of power storage but also signaling and electronic noise filtering  For an abbreviated explanation of how these devices work, watch this video published by The Engineering Mindset.

Unfortunately, capacitors, like most things, have a finite lifespan. And, when they fail, they can take the entire system with them.

The Common Causes of Capacitator Failure

While a small percentage of capacitors make it to the end of their expected lifespan, many die out before their expiration date.  This premature death is caused by either dielectric breakdowns (a.k.a. shorts) or a sudden opening at one end of the capacitor. The reasons for these failures are environmental stressors like:

    • Power Outages and Surges: Storms and extreme weather can deprive systems of power. When electricity returns, it can sometimes do so in a sudden burst of high voltage. If not protected from this sudden deluge, capacitors can burst.
    • Age: Like bones, capacitors and their components become more brittle over time. As they reach the end of their manufacturer-stated usefulness, the likelihood of a sudden failure increases.
    • Heat: There are a couple of reasons high-voltage systems and consumer electronics come equipped with fans and venting. Capacitors are one of those. When the temperature of one rises outside its stated tolerance, the gas inside the capacitor can expand leading to explosions and device failure. This issue is especially common in electrolytic capacitors.
    • Cold: Electrolytic capacitors become less effective when they’re exposed to temperatures below 25 degrees Celsius. Unlike with heat, however, the damage is not permanent. In most cases, the device reaches full capacity once its warmed back up.
    • Moisture: If a capacitor’s casing begins to fail, it will be exposed to outside humidity. This can lead to gross parametric changes, reduced service life, and sudden failure. Paper-dielectric, non-hermetically sealed capacitors are most susceptible to this stressor.
    • Dynamic Shifts Excessive shock or vibration can shorten the lifespan of a capacitor. The movement caused by these environmental changes can lead to capacitance fluctuations, electrode detachments, and insulation failure. The degree of sensitivity to this stressor is often dependent on a capacitor’s construction. Typically, the larger the capacitor, the less movement matters.
    • Barometric Pressure: This pressure determines the altitude at which a hermetically sealed capacitor can operate safely. The design of the case-wall and recommended voltage work in tandem to determine how far from sea level a given system can operate.
    • Radiation: Radiation particles can lower the electrical performance of a capacitor. This is due to a change in interelectrode spacing. In an ionizing-radiation environment, this can lead to a sudden discharge of energy. While most capacitors are susceptible to this stressor, it’s more pronounced in organic-dielectric capacitors.

How a Little Piece of Rubber Can Help

Can you imagine tossing out a multi-million-dollar industrial system because someone jostled a chipboard a little too hard? Or constantly repairing a fault HVAC model because it’s prone to capacitor overheating? Fortunately, protecting yourself from these issues doesn’t mean rewiring your whole system. In many cases, it’s enough to add a capacitor cap.

Also known as capacitor boots, these little hunks of plastic protect wire terminals from moisture, temperature fluctuations, vibrations, and sudden shocks. Put simply, they’re a coat of armor for your capacitor. They’re also protect maintenance employees from accidental shocks. Using them is as simple as slipping one over the capacitor and pulling the wires through the pre-drilled holes.

If you need a replacement boot, it’s best to ship the failed part to your supplier. For retrofitting on a system without any secondary protection, start by measuring the height of your capacitors. Then, determine the number of wire holes needed. While many capacitor caps are cylindrical, they can be designed to fit almost any device.

Are You Looking for Custom Capacitator Boots?

Installing high-end capacitor boots in your electronic systems can reduce the likelihood of system failure and protect your employees from unintentional shocks. Typically costing under a dollar per piece, there’s rarely a circumstance in which they’re a bad investment. Rest assured, no matter the diameter or configuration of your capacitor boot, that our rubber extrusion experts can help.

Reach out to us at 510-895-6001 to get a quote on after-market capacitor caps or custom injected pieces.