The 220V DC system supplies direct current as source of operating power for control, signaling, relays, tripping and closing of switchgears, emergency motors of most important auxiliary systems. Under normal conditions of station generation, the storage battery units are kept floating in DC bus bars by means of the trickle chargers (also known as float …
Purpose and maintenance of transformer bushings
The two most common types of bushings used on transformers as main lead entrances are solid porcelain bushings on smaller transformers and oil-filled condenser bushings on larger transformers. Solid porcelain bushings consist of high-grade porcelain cylinders that conductors pass through. Outside surfaces have a series of skirts to increase the leakage path distance to the …
Retro perspective 30 years ago: Metal-Clad or Metal-Enclosed MV Switchgear? What to choose?
There are two types of switchgear commonly applied today for switching and protection of in-plant medium voltage (4.16 kV through 34.5 kV) power distribution systems. One is metal-clad switchgear using draw-out air-magnetic or vacuum circuit breakers and relays for both load switching and fault protection: the other is metal-enclosed switchgear using interrupter switches for load switching …
The Importance of the Correct PPE
Whilst awareness of the dangers of arc flash has continued to increase over the last few years, the number of incidents that are still occurring on a daily basis are shockingly high. Arc flash incidents are the greatest threat to the wellbeing of any electrical worker and can lead to serious injury and in some …
Testing of UPS devices
The purpose of electrical testing on systems and their components is two-fold. The first is to check the installation of the equipment and perform component and systems tests to ensure that, when energized, the system will function properly. The second is to develop a set of baseline test results for comparison in future testing to …
Maintenance Of Meduim Voltage Circuit Breakers
Medium-voltage circuit breakers rated between 1 and 72 kV may be assembled into metal-enclosed switchgear line ups for indoor use, or may be individual components installed outdoors in a substation. Air-break circuit breakers replaced oil-filled units for indoor applications, but are now themselves being replaced by vacuum circuit breakers (up to about 35 kV). Medium …
Maintenance Of SF6 Gas Circuit Breakers
Sulfur Hexafluoride (SF6) is an excellent gaseous dielectric for high voltage power applications. It has been used extensively in high voltage circuit breakers and other switchgears employed by the power industry. Applications for SF6 include gas insulated transmission lines and’gas insulated power distributions. The combined electrical, physical, chemical and thermal properties offer many advantages when …
Maintenance Of Molded Case Circuit Breakers (MCCB)
The maintenance of circuit breakers deserves special consideration because of their importance for routine switching and for protection of other equipment. Electric transmission system breakups and equipment destruction can occur if a circuit breaker fails to operate because of a lack of preventive maintenance. The need for maintenance of circuit breakers is often not obvious …
Maintenance Of Low Voltage Circuit Breakers
The deterioration of low voltage circuit breaker is normal and this process begins as soon as the circuit breaker is installed. If deterioration is not checked, it can cause failures and malfunctions. The purpose of an electrical preventive maintenance and testing program should be to recognize these factors and provide means for correcting them. A …
Maintenance for UPS systems
Maintenance of the UPS consists of preventive and corrective maintenance. Preventive maintenance consists of a scheduled list of activities. Performing these activities keeps the UPS in good working order and helps to prevent failures. Corrective maintenance is performed as a result of a failure. Corrective maintenance fixes the problem and gets the unit working again. …
