Old and Outmoded Switchgears

Addressing Deficiencies in Safety and Efficiency Standards

Modern day technologies bring about increases in demand for electrical power, which likewise intensify the stresses imposed on electrical installations. Electrical components tend to wear out at a faster rate, while deterioration in insulation will cause inefficiency that can lead to malfunctions. Such conditions tend to elevate the electrical faults at levels that lead to performance failures. In most cases, electrical malfunctions compromise the safety of operators and other workers in the vicinity, and cause damage to the building as well.

Problems Associated with Old and Outmoded Switchgears

A switchgear installation for one, particularly the old and outmoded type, cannot be expected to operate in the same condition by which it was originally designed. Basically, the standards that were met during its manufacture around twenty to thirty years ago are now regarded as deficient in relation to the changes brought about by the continuous development and advancements in technology. Certain considerations are often overlooked, such as the modifications that have taken place in the network that feeds electrical current to the switchgears.

Nearby substations step-down the voltage transmitted to the local distribution circuits of factories and other industrial customers. The incoming electrical power will be converted into several smaller voltages in the electrical system, by the switchgear. These smaller voltages will power up the fixtures, machineries and equipment within a plant or building, by way of the isolated circuits in which electrical current flows inside the electrical distribution system.

The protective features of the switchgear include the circuit breakers, which help in managing the multiple electrical feeds in a single area. Should a short circuit occur, only the low resistance area that was affected by the unintended flow of electric current will be interrupted, instead of causing electrical malfunction throughout the building. However, as the demand for electrical power increases, short circuits tend to occur more frequently due to the limited capacity of the circuits. These occurrences will overstress the switchgear to the point of exceeding its fault energy rating.

A switchgear that has disconnect switches, allow for repairs and maintenance in order to clear the faults that may be taking place in an electrical system. Otherwise, if the switchgear continues to operate under fault conditions, the effect of the excessive electrical and thermal stress can lead to loose or damaged connections. Such conditions tend to produce sparks or arcing flashes between connections and these are capable of melting wire insulations. Faulty wires and connections, as we all know, are the leading causes of electrical fires.

Outdated designs such as dependent manually operated (DMO) switchgear, pose as hazards because the operator has to manually open or close the DMO apparatus by way of a lever or handle. However, any indecisive action in closing or opening the switchgear could prove to be a fatal mistake on the part of the operator. If the defect in the circuit produces arc flashes which are often difficult to detect, the sparks may have cooled down for awhile but can heat up again in a matter of seconds. This can produce a burst of burning oil or hot gasses that could blow-up in the operator’s face. Such incidents can be catastrophic and have been known to cause serious burn injuries and even fatalities.

Management and Maintenance of Switchgear Operations

Problems due to old and outmoded switchgears usually arise if there is lack of proper maintenance. In some cases, new building occupants or new switchgear operators are unaware of the electrical installation’s operational limitations or present conditions.

Best practices recommend that if there is uncertainty or lack of knowledge about the electrical systems that are in place, an inventory should be performed as a matter of priority. First off, there should be a careful study of the schematic presentation of the electrical network. A diagram will show the interconnections in the entire set-up, including those that pertain to switchgear operations. Most importantly, the diagram should be clear enough to pinpoint the bottleneck areas where electrical overloads tend to occur.

Switchgears that were properly maintained usually have records that provide information about:

    • The manufacturer, year manufactured and item type
    • The location and date of installation
    • The voltage rating, current rating and fault rating (whether assigned, certified or assessed)
    • Operating mechanism whether DMO, independent manual, dependent or independent power and stored energy
    • Modifications made, e.g. anti-reflex handles, internal-arc fault retrofits and other types of electrical protection
    • Type of circuit breaker whether oil, ground fault interrupter (GFI), thermal, magnetic or combined heat and electromagnetic
    • Date of last maintenance and the number of fault operations that were cleared.

Lest, there is not enough technical expertise in carrying out the audits, the risk assessments and the formulation of precautionary or mitigation measures to put in place, appropriate sources of information include:

    • Power distribution companies
    • switchgear manufacturers
    • Switchgear maintenance companies, preferably those with adequate knowledge and expertise in older types of switchgears
    • Consultants who specialize in switchgear operations

Pay heed to the results of the review, tests, and assessments conducted by the above-mentioned switchgear experts; whether there is a need to replace the old switchgear or to overhaul the unit.¬†Although management should decide by considering the plant’s priorities, since replacements may involve:

Replacing the switchgear units – this comes with the benefits of attaining optimum lifespan and having safety protections. Yet, this involves intensive capital investments; hence, there should be a careful deliberation over the lifespan of the plant as a whole and the life expectancy of the new switchgear. Priorities must also be established to allow putting in place replacements without hampering the flow of operations, or cause delays in meeting commitments. The matter of prioritizing includes the budget of the company and its capacity to meet unplanned major capital expenditures.

Overhauling or refurbishing of the individual switchgear units – Prior to embarking on this solution, there should be a thorough evaluation of the switchgear parts that will be retained. This includes determining if the remaining life of the parts to be retained matches the life expectancy after the overhauled switchgear; or if the ratings between the retained and the new parts are compatible. Overhauling as a corrective measure should also include determining the availability of spare parts from the original manufacturer of the equipment; from the successor company if the original manufacturer has been absorbed by a larger firm; or from small engineering companies that specialize in fabricating or reconditioning the switchgear parts.

Examples of refurbishing include but are not limited to:

    • Upgrading switchgear ratings, after making an assessment of the load rating, e.g. from 480V to 15KV;
    • Upgrading bus with new plating;
    • Installation of new wirings;
    • Frame restoration;
    • Upgrading the switchgear with modern protective components; and
    • Other necessary replacements that may surface after testing the full capabilities of the overhauled apparatus.

Retrofitting the Circuit Breakers of the switchgears – Retrofitting denotes adding new or modern components to an existing equipment, to improve the circuit breaker ratings and safety features that are usually lacking in antiquated or outmoded switchgear installations.

Retrofits may include:

    • Modifying an oil circuit breaker by incorporating a vacuum or sulfur hexafluoride (SF6) and an internal arc rating that will vent hot gasses away from the operator.
    • Lessening the risk in dependent manually operated switchgears by adding remote actuator mechanisms.
    • Integrating arc detection systems that can clear any existing faults in a matter of milliseconds
    • Based on these examples, it is quite clear that modern technology can extend the efficiency and life expectancy of outmoded and old switchgear units, as a means to enhance safety controls as well as meet the current standards.

Contact East Coast Power Systems and we will help you determine if your Switchgears are too old or outmoded.