Components within a medium voltage power system are subjected to harsh electrical and environmental conditions, and the reliability of an insulation system is critical for the continued distribution of electrical energy without interruption. Electrical stress, temperature extremes, moisture, dirt and industrial pollution are all present on components such as transformers, switches, Ring Main Units (RMU’s), and cable terminations. In medium voltage installations, one of the most critical components is the bushing; therefore, it needs to be insulated properly in order to prevent failure or damage from around it. This is where medium voltage cold applied bushing protection boots are extremely valuable.

What is Bushing

A bushing is an insulated device used to permit the safe passage of an electrically conductive object (conductor) through the grounded/earthed portion of an apparatus (such as a transformer, switchgear panel, circuit breaker, or electric control cabinet). It provides electrical insulation between the live conducting components and the metallic parts of the apparatus while allowing electrical current to flow through the power system.

Why It Needs Protection

If a bushing is exposed to moisture, contaminants (ex. dirt), ultraviolet exposure (UV), and/or industrial materials (ex. VOC’s, sulfur, etc), it can develop degradation of its insulation surface, which can create an increased susceptibility to electrical fault occurrences. Proper bushing protection helps maintain insulation reliability and extends the operational life of medium voltage systems.

How Cold Applied Boots Protect Bushings

Additional Electrical Insulation

By covering exposed electrical elements with cold applied boots, an extra layer of insulation is added over the exposed conductive elements. This additional insulation supports an insulated air space between the energized parts of electrical apparatuses and surrounding equipment, lessening the chances of a fault due to an electrical condition or inadvertent contact.

Protection Against Electrical Tracking

Electrical tracking takes place when there is enough moisture and contaminants combined on the surface of an insulation to create a conductive carbonized path. Continued tracking will harm the insulation over time and can eventually lead to total failure of the insulation. Medium voltage Cold applied bushing protection boots have high tracking resistance, along with a smooth surface of insulation to help reduce the opportunity for leakage currents and surface discharges.

Prevention of Moisture Entering

In the medium voltage systems, moisture is one of the leading culprits of insulation failure. Rainwater, high humidity, and condensation can create conductive paths on exposed surfaces and increase the risk of an electrical discharge.

Reduction of Flashover Risk

Cold applied boots improve insulation protection around critical connection points and significantly reduce the likelihood of flashovers in medium voltage systems.

Conclusion

Bushing protection is an essential part of medium voltage power system reliability and safety. Exposed bushings are constantly affected by electrical stress, moisture, contamination, and environmental conditions that can lead to insulation failure if left unprotected. Medium voltage Cold applied bushing protection boots provide an effective solution for this by providing increased insulation capability, moisture sealing, resistance to contamination, and preventing flashovers, in addition to being cost-effective to manufacture and install.