Electrical Distribution Equipment Failure – Keep or Discard

When dealing with electrical equipment and components it is inevitable that they will fail, and you will have to deal with the consequences.  The minute electrical equipment is put into place, from transformers to circuit breakers and panel switches and tap boxes, they start to decline.  Deterioration of electrical products happens for a number of reasons including:

• Moisture Absorption
• Differing Temperature Cycles
• Dust and Particles Settling
• Condensation Buildup
• Fragile Operating Springs
• Insulation Material Breakdown
• Rusted Out Switchgear Enclosures
• Dried Out Capacitors

When electrical components within distribution systems age vulnerabilities start to appear. With automation being what it is today, electrical technology can often run unassisted, without issue for years. Because of this maintenance on these systems tend to be ignored which can lead to unpredicted failures which lead to catastrophic failures; the most common being fire.  Thus, in order to keep electrical components operating at their peak and delivering consistent power renovations and maintenance are critical.

The two biggest nemeses of electrical equipment and the components within are moisture, condensation, dust, and loose particles. When equipment is installed outdoors or in spaces that offer no type of temperature or humidity control deterioration occurs more rapidly then in spaces where there are controls, just at a slower, more gradual pace. 

Based on the quality, maintenance schedule, and environment of electrical equipment and components that are installed the deterioration rate varies.  When planning for maintenance, upkeep, and refurbishment of electric components and equipment it is important to establish the age and overall condition of each piece. 

Electrical Equipment and Component Insulation

Components within each piece of equipment must be inspected individually.  Insulation is the component of electrical equipment that degrades the quickest.  Paper and solid synthetic insulation is used throughout equipment around motors, capacitors, cables, transformers, circuit breaker trip coils, operating coils of contractors, and reactors.  The breakdown of insulation depends a great deal on the temperatures that it is exposed to.  To increase longevity of equipment and decrease the breakdown of insulation it is important for equipment not to be operated above optimal temperature ratings.

Capacitors in Electrical Equipment

There are various types of capacitors used in both low and medium voltage distribution systems including:

• Surge Capacitors
• Power Factor Correcting Capacitors
• Commutating Capacitors
• Capacitors in Active and Passive Filters
• Pole-Mounted Capacitors

The most common capacitor to use in ratings up to several hundred kVAR is power factor correction.  They are sealed in airtight, insulated units for protection.  The insulating material that is used is a metalized polypropylene film that is compressed in a thermal setting resin.  In the event of internal failure, pressure sensitive interrupters are used to disconnect the capacitor. Capacitors are always fused externally because their failure is most often due to circuit shorts.

There is a nonstop loss of power internally because of lag thus causing the insulating resin to dry.  This often goes unnoticed.  Most capacitors have an average life expectancy of about seventeen years when in continuous operation. This of course decreases depending on the environment in which it operates.  Many systems have a decrease in this average life expectancy due to being exposed to over use and variation in frequency.  To check measurements for capacitors, use clamp-on ammeter to test and detect disparity over time.  

In our next installment we will dive deeper into more electrical components and how they work, their longevity, usage, and testing.  Such components we will inspect will include transformers, circuit breakers, reactors, cables, relays, and more.

J & P Electrical Company is a full-service electrical company that supplies contractors, end users, and supply houses with new surplus, quality reconditioned, and obsolete electrical equipment. We purchase a wide range of electrical equipment such as bus plugs, bud ducts, panel switches, substations, and transformers.  More information can be found at https://www.jpelectricalcompany.com