PSIM Software

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PSIM Software

PSIM Software

PSIM is one of the fastest simulators for power electronics simulation. It achieves fast simulation while retaining excellent simulation accuracy. This makes it particularly efficient in simulating converter systems of any size, and performing multiple-cycle simulation.

PSIM is the engine of the simulation environment. PSIM uses a strong algorithm dedicated to electrical circuits (piecewise method, generic models and a fixed time-step). The fast simulation allows repetitive simulation runs and significantly shortens the design cycle.

PSIM can simulate control circuit in various forms: in analog circuit, s-domain transfer function block diagram, z-domain transfer function block diagram, custom C code, or in Matlab/Simulink®. PSIM’s control library provides a comprehensive list of components and function blocks, and makes it possible to build virtually any control scheme quickly and conveniently.

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The Switchboard Design Requirements

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Switchboard Panel

The Switchboard Design Requirements

Design Rules

The following rules of design have to be implement in the aim to facilitate the assembly and especially the maintenance of the installation.

 The switchboard must be designed the way to have a clearly visible separation between the 3 following zones:
  • One dedicated for the devices installation
  • One dedicated for the bus bars mounting
  • and one dedicated for the out-goers cables connections 

Switchboard Areas

The goal of that architecture is to separate the switchboard in different areas in function of each professional user.
  • Devices zone => panel builder and exploiter
  • Bus bars zone => panel builder
  • Cable connection zone => installer and maintenance

In order to facilitate the access within the switchboard for the maintenance, its covering panels must be dis-mountable on all surfaces for any IP degree.

All the devices must be installed onto dedicated mounting plate designed for one or several switchgear of the same type. The objective of that point is to regroup the protection equipment of the same nature each others and distinguish inside the switchboard the function of each device or group of devices.

Theses mounting plates will have an independent fixing system affording them to be transformed and moved anywhere in the switchboard and especially to make it easier the installation evolution.
To insure the maximum protection of people around the electrical installation, front plates must be installed in front of all control and protection equipment in order to avoid a direct access without a tool to the devices and consequently to the active parts.

For safety reasons and especially when the door will be opened during the switchboard working, all bus bars have to be covered by barriers onto the whole perimeter of the bus bars zone.

Maintenance Of Meduim Voltage Circuit Breakers

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Medium Voltage Circuit Breaker

Maintenance Of Medium 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 voltage circuit breakers which operate in the range of 600 to 15,000 volts should be inspected and maintained annually or after every 2,000 operations, whichever comes first.

The above maintenance schedule is recommended by the applicable standards to achieve required performance from the breakers.

Maintenance procedures include the safety practices indicated in the ROMSS (Reclamation Operation & Maintenance Safety Standards) and following points that require special attention.
  • Be sure the circuit breaker and its mechanism are disconnected from all electric power, both high voltage and control voltage, before it is inspected or repaired.
  • Exhaust the pressure from air receiver of any compressed air circuit breaker before it is inspected or re­paired.
  • After the circuit breaker has been disconnected from the electrical power, attach the grounding leads properly before touching any of the circuit breaker parts.
  • Do no lay tools down on the equipment while working on it as they may be forgotten when the equipment is placed back in service.

Maintenance Procedures For:

Medium Voltage Air Circuit Breakers

The following suggestions are for use in conjunction with manufacturer’s instruction books for the maintenance of medium voltage air circuit breakers:
  1. Clean the insulating parts including the bushings.
  2. Check the alignment and condition of movable and stationary contacts and adjust them per the manufacturer’s data.
  3. See that bolts, nuts, washers, cotter pins, and all terminal connections are in place and tight.
  4. Check arc chutes for damage and replace damaged parts.
  5. Clean and lubricate the operating mechanism and adjust it as described in the instruction book. If the operat­ing mechanism cannot be brought into specified tolerances, it will usually indicate excessive wear and the need for a complete overhaul.
  6. Check, after servicing, circuit breaker to verify that contacts move to the fully opened and fully closed positions, that there is an absence of friction or binding, and that electrical operation is functional.

 

Medium Voltage Oil Circuit Breakers

The following suggestions are for use in conjunction with the manufacturer’s instruction books for the maintenance of medium-voltage oil circuit breakers:
  1. Check the condition, alignment, and adjustment of the contacts.
  2. Thoroughly clean the tank and other parts which have been in con­ tact with the oil.
  3. Test the dielectric strength of the oil and filter or replace the oil if the dielectric strength is less than 22 kV. The oil should be filtered or replaced whenever a visual inspection shows an excessive amount of carbon, even if the dielectric strength is satisfactory.
  4. Check breaker and operating mechanisms for loose hardware and missing or broken cotter pins, retain­ ing rings, etc.
  5. Adjust breaker as indicated in instruction book.
  6. Clean and lubricate operating mechanism.
  7. Before replacing the tank, check to see there is no friction or binding that would hinder the breaker’s operation. Also check the electrical operation. Avoid operating the breaker any more than necessary without oil in the tank as it is designed to operate in oil and mechanical damage can result from excessive operation without it.
  8. When replacing the tank and refilling it with oil, be sure the gaskets are undamaged and all nuts and valves are tightened properly to prevent leak­ age.

Medium Voltage Vacuum Circuit Breakers

 

Direct inspection of the primary contacts is not possible as they are enclosed in vacuum containers. The operating mechanisms are similar to the breakers discussed earlier and may be maintained in the same manner. The following two maintenance checks are suggested for the primary contacts:
  1. Measuring the change in external shaft position after a period of use can indicate extent of contact erosion. Consult the manufacturer’s instruction book.
  2. Condition of the vacuum can be checked by a hipot test. Consult the manufacturer’s instruction book.



ABB – 145kV Compact indoor substation with Disconnecting CB

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ABB – 145kV Compact indoor substation with Disconnecting CB

Turnkey 145 kV S/S project for Borlänge Energi, Sweden, emphasizing the advantages of ABB Disconnecting Circuit Breakers. Small footprint enables indoor air insulated Switchgear solutions, increasing the power substation availability and reliability for the customer.
As a complement to the basic version of our LTB circuit breakers, which are primarily designed for conventional substation solutions, there is a disconnecting circuit breaker configuration with the disconnecting function integrated in the breaking chamber.

The LTB Disconnecting Circuit Breaker (DCB) is based on the LTB standard circuit breaker. The disconnecting function is integrated in the breaking chamber. That means that the circuit breaker fulfills all requirements for a circuit breaker as well as all requirements for a dis-connector. A safe interlocking system, composite insulators and a motor driven grounding switch provide personal safety.

With DCB we have created the capability to design substations without conventional dis-connectors, which improves operational availability.

Basic Refrigeration Cycle

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Basic Refrigeration Cycle

Principles of Refrigeration

  • Liquids absorb heat when changed from liquid to gas
  • Gases give off heat when changed from gas to liquid.
For an air conditioning system to operate with economy, the refrigerant must be used repeatedly. For this reason, all air conditioners use the same cycle of compression, condensation, expansion, and evaporation in a closed circuit. The same refrigerant is used to move the heat from one area, to cool this area, and to expel this heat in another area.
  • The refrigerant comes into the compressor as a low-pressure gas, it is compressed and then moves out of the compressor as a high-pressure gas.
  • The gas then flows to the condenser. Here the gas condenses to a liquid, and gives off its heat to the outside air.
  • The liquid then moves to the expansion valve under high pressure. This valve restricts the flow of the fluid, and lowers its pressure as it leaves the expansion valve.
  • The low-pressure liquid then moves to the evaporator, where heat from the inside air is absorbed and changes it from a liquid to a gas.
  • As a hot low-pressure gas, the refrigerant moves to the compressor where the entire cycle is repeated.
Note that the four-part cycle is divided at the center into a high side and a low side This refers to the pressures of the refrigerant in each side of the system.

 

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