Electrical Standoff Insulators
Although standoff insulators perform an ancillary function within most electrical systems, they can be critical for maintaining a device’s operational capability. A standoff insulator typically supports a conductor at a distance from the surface, or substrate, to which it is attached. The insulator’s high electrical resistance prevents the unintentional flow of current between a conductor and surrounding objects, effectively reducing the potential for power damage and energy waste.
Standoffs are used as separators in electronic and mechanical industries. They can be produced from a variety of materials, and come in a range of dimensional categories. For an insulator, the standoff format is particularly useful, as it eliminates any direct physical contact between electrical components that may cause them to short out. To better understand if standoff insulators are necessary for a given project, it may be helpful to review electrical operations as well as the different types of insulators currently available.
Conduction vs. Insulation
Conductors function under the principle that a charge will move through any material in which electrons can be excited. Perpetuating the charge builds energy and creates an electrical flow through a conductive substance. An insulator is any substance lacking the physical properties to excite electrons and extend the charge—this is usually due to the “band gap,” which constitutes the difference between a material’s valence (the strength of its atomic bonds) and its conductivity (the degree to which it can carry a current).
Insulators typically have strongly bonded valence electrons, preventing them from entering an excited state. However, if sufficient voltage is applied, the electrons will overcome their bonds and become charged, causing the insulator to become a conductor. This is usually accompanied by some form of material damage that alters the former insulator’s physical properties.
The material used to create an insulator can greatly influence its effectiveness in certain applications. Manufacturers typically produce porcelain insulators from clay, quartz, or feldspar rock. They can tolerate high voltage or electrical stress, and reliably regulate the flow of charge. In addition, porcelain has high tensile strength, corrosion resistance, and deformation resistance.
However, ceramics are susceptible to fracture due to their rigidity. Composite materials are common alternatives to ceramic-based insulators, as they alleviate the potential for cracking. A composite, such as a fiberglass core sheathed in rubber, can provide greater physical flexibility and moisture resistance, but with lower voltage tolerance and a faster rate of wear than its ceramic counterpart.
Plastic insulators are usually made from polymer resins, such as polypropylene or polyethylene. They are highly versatile and tend to be less expensive than ceramic or composite materials. Prolonged exposure to ultraviolet light can, however, increase their frailty and chance of shattering.
Standoff Insulator Applications
A standoff insulator is mounted at a distance from the electrical component it supports, and functions essentially as a threaded spacer. The most important specifications for a standoff insulator are its electricity clearance, mechanical strength, and mounting procedure. They are most commonly used for regulating current in conductors, or in conductive components of switchgear and transformers (though the units are typically designated by insulating medium rather than arrangement).
Due to the physical separation between the insulator and the component, standoffs usually control the flow of a high level of voltage, and significantly reduce the chances of inter-component shortages. This is especially useful in powering stations or electrical devices that have high energy requirements and electrically-sensitive equipment.
In deciding whether a standoff is right for a particular application, the insulating material, conductive strength, and environmental conditions are important factors. However, the proximity and electrical resistance of the device to be supported is likely the central concern in selecting an insulator.