Sabtu 22 oktober 2011

Hello world udah lama gag buka internet,i am very busy because of works matter 

this note i am wrote in my office when i am bored with my job,

i try to share my knowledge about Static Transfer Switch

The static transfer switch (STS) is an electrical device that allows instantaneous transfer of power sources to the load. This superior switching time means that if one power source fails, the STS switches to the back-up power source so quickly that the load never recognizes the transfer made. The STS is classified as low voltage STS (voltages up to 600V, current ratings from 200 amps to 4,000 amps) and medium voltage STS (voltages from 4.16KV to 34.5KV).

Fast-acting STS's that can transfer between two power sources in four to 20 milliseconds are increasingly being applied to protect large loads and entire facilities from short-duration power disturbances. These products use solid-state power electronics or "static" switching as compared to electromechanical switches, which are too slow for the application. Electromechanical switches are found in automatic transfer switches (ATS) for transferring building loads to emergency or stand-by generators.

The basic STS unit consists of three major parts:

• Controls and metering
• Silicon-controlled rectifiers
• Breaker/bus assembly

The STS monitors two power sources and automatically shifts to the better one on sensing the failure or degradation of either source. There is no wear and tear associated with this process.

Low Voltage Static Transfer Switch (LV-STS)

A LV-STS can transfer at a low voltage (less than 600V) between two power sources in four to 20 milliseconds. LV-STSs are applied to protect large loads and entire facilities. LV-STS includes both static and hybrid types. LV-STS can be used as a stand-alone system or in conjunction with power distribution units or uninterruptible power supplies (UPS).

These low voltage switches are available in voltages up to 600V in current ratings from 200 amps to 4,000 amps. LV-STS is applied to the critical equipment or to groups of loads or at the service entrance of a building.

A LV-STS is often employed synergistically with UPSs. However, it also competes with UPSs and other power quality equipment types for applications. For example

• Data centers typically isolate the critical load and may employ LV-STS with dual-redundant UPSs as the power sources
• An industrial plant may choose to use LV-STS with dual-redundant UPS's as the power sources
• An industrial plant may choose to use LV-STS on isolated groups of critical process equipment

The same industrial user may instead choose a facility-scale system (medium-voltage STS, custom power, microSMES, or BESS) to protect the entire plant, particularly if the critical process cannot be easily isolated from other independent manufacturing steps.

Capital cost for LV-STS equipment is typically lower than it is for a UPS, provided two independent power sources are available. From an operating expense point of view, LV-STS has lower costs over continuously operating UPSs because there is no large rectifier/inverter subsystem to power. LV-STS takes less real estate than a UPS, and at least the transformer components of LV-STS are capable of outdoor installation.

Some application areas where LV-STS are used:

• Critical IT operations
• Telecommunication
• Network operations centers
• Fiber optic nerve center
• Process control
• Data centers
• Airport security system
• Commercial buildings
• Power generation plants
• Utilities

The demand for LV-STS will depend on the growth in end-user application areas. The data centers, telecommunication, airport security system, banks and financial institutions, manufacturing and service industry among others will contribute to the growth of the LV-STS market. Some of the major manufacturers of the LV-STS include Liebert Corporation, Cyberex, MGE UPS, Socomec, Level 3 Communication (Power Paragon), Piller, Inc., Chloride Power, GE Zenith, PDI, and Silicon Power Corporation.

Medium Voltage Static Transfer Switch (MV-STS)

The MV-STS, which was introduced in the market in 1995, can transfer at a medium voltage (4.16 kV to 34.5 kV) between two power sources in four milliseconds or less. MV-STS and custom power products are applied at the substation or service entrance of large facilities. The MV-STS is increasingly being applied to protect large loads and entire facilities by rapidly transferring to a second power source upon detection of a power disturbance on the primary supply. A typical application of the MV-STS would be at the substation or service entrance of a large industrial plant.

Some applications of the MV-STS are:

• Automated manufacturing
• Automotive assembly lines
• Telecommunication centers
• Computer networks
• E-commerce businesses
• R&D labs
• Commercial buildings
• Power quality and industrial parks
• Commercial printing machines
• Internet data centers
• Semiconductor industry

MV-STS has the design goal of protecting an entire building or facility from power disturbances originating from utility feeders. Nationwide surveys have demonstrated that the greatest number of power disturbances is the result of faults on utility systems that are cleared in less than 10 seconds. Fast switching of an MV-STS to an alternate feeder will solve many of these problems especially if the alternate feeder is on a different substation transformer. MV-STS is technically unique in their ability to protect at the facility, campus, or wide-area level.

The demand for MV-STS will depend on the growth in end-user application areas. The semiconductor, automated manufacturing, car assemblers, telecommunication, pharmaceuticals among others will contribute to the growth of the MV-STS market. Some of the major manufacturers of the MV-STS include S&C Electric, Silicon Power Corporation, SatCon Power Systems (Inverpower Controls), ABB, and Cutler-Hammer.

Conclusion

The STS market has a potential to grow during the coming years. The demand for STS is likely to increase due to the importance of providing continuous power supply to a critical application/load.

The main challenges affecting the STS market include:

• Reduced capital spending limiting STS end-user demand
• Economic conditions retarding vendors' short-term growth
• Ability to adapt to changes in technology, determining the winners in the market
• Effectively targeting and utilizing resources
• Price pressure affecting growth in the static transfer switch market revenue
• The slow pace of electric utility deregulation is creating uncertainty in the business environment
• Responsiveness to customer needs

These challenges have a varying effect on the market.

Participants in the STS market must stay abreast of the latest technologies and developments in the industry. They should constantly work toward designing and manufacturing quality devices that have added features and performance capabilities in order to meet the end-users' needs and requirements. By becoming part of key associations in the industry as well as conducting regular analysis of their targeted end-user segments manufacturers are likely to develop an important competitive advantage in this developing market.