Many adjustable-speed drives are equally sensitive to voltage sags as process control equipment discussed in the previous section. Tripping of adjustable-speed drives can occur due to several phenomena: • The drive controller or protection will detect the sudden change in operating conditions and trip the drive to prevent damage to the power electronic components. • […]
ADJUSTABLE SPEED AC DRIVES BEHAVIOR DUE TO VOLTAGE SAG Read More »
During a short interruption the voltage is zero; thus, there is no supply of power at all to the equipment. The temporary consequences are that there is no light, which motors slow down, that screens turn blank, etc. All this only lasts for a few seconds, but the consequences can last much longer: disruption of
INFLUENCE OF SHORT INTERRUPTIONS ON EQUIPMENT Read More »
As short interruptions are due to automatic switching actions, their recording requires automatic monitoring equipment. Unlike long interruptions, a short interruption can occur without anybody noticing it. That is one of the reasons why utilities do not yet collect and publish data on short interruptions on a routine basis. One of the problems in collecting
MONITORING OF SHORT INTERRUPTIONS Read More »
Long interruptions are always due to component outages. Component outages are due to three different causes: I. A fault occurs in the power system which leads to an intervention by the power system protection. If the fault occurs in a part of the system which is not redundant or of which the redundant part is
CAUSES OF LONG INTERRUPTIONS Read More »
Switchgear covers a wide range of equipment concerned with switching and interrupting currents under both normal and abnormal conditions. It includes switches, fuses, circuit breakers, relays and other equipment. A brief account of these devices is given below. However, the reader may find the detailed discussion on them in the subsequent chapters. 1. SWITCHES A
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The essential features of switchgear are: (I) COMPLETE RELIABILITY With the continued trend of interconnection and the increasing capacity of generating stations, the need for a reliable switch-gear has become of paramount importance. This is not surprising because switchgear is added to the power system to improve the reliability. When fault occurs on any part
ESSENTIAL FEATURES OF SWITCHGEAR Read More »
The apparatus used for switching, controlling and protecting the electrical circuits and equipment is known as switchgear. The switchgear equipment is essentially concerned with switching and interrupting currents either under normal or abnormal operating conditions. The tumbler switch with ordinary fuse is the simplest form of switchgear and is used to control and protect lights
An induction regulator is essentially a constant voltage transformer, one winding of which can be moved w.r.t. the other, thereby obtaining a variable secondary voltage. The primary winding is connected across the supply while the secondary winding is connected in series with the line whose voltage is to be controlled. When the position of one
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Sometimes it is desired to control the voltage of a transmission line at a point far away from the main transformer. This can be conveniently achieved by the use of a booster transformer as shown in Figure 1. The secondary of the booster transformer is connected in series with the line whose voltage is to
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Figure shows diagrammatically auto-transformer tap changing. Here, a mid-tapped auto-transformer or reactor is used. One of the lines is connected to its mid-tapping. One end, say a of this transformer is connected to a series of switches across the odd tappings and the other end b is connected to switches across even tappings. A short-circuiting
AUTO TRANSFORMER TAP CHANGING Read More »