GENERATOR is one of the most important electricity distribution systems. It works as a backup power generator in case of power outage, so that the various units have continual electricity for use.
Installation considerations for generator
– Location. Consider the wind blowing in and out of the room. Away from dusty environments, chemical, impurities and high humidity.
– Room Layout. Normally it requires approximately 1.5-2 meters space around the generator for maintenance and for the main power supply, oil pipeline, air duct and exhaust pipes area.
– Room Ventilation. It requires good ventilation system to ventilate the room and generators. The air will flow from the rear to the front. There must be vents of the size that suits the size of generator.
– Foundation. It must be able to support the weight of the generator including reaction force caused by vibration of the machine. It should be raised about 10-15 cm from the floor and should be larger than the base of the machine at least 200-400 mm in each side.
– Exhaust pipe installation. Exhuast pipe should be short and fits the size of installation site. It should have minimum amount of elbow pipe. In case of the installation of more than 10 meters, the diameter of the pipe should be increased by depending on the length and the number of elbow pipe used.
Use caution when using generator
– Usage. Do not use generator exceeding the limitation stated in the name plate, whether use in temporary or permanent work. However, for continuous use, generator can sometimes run with 10% overload.
– Voltage. A generator is a part which produces electricity to supply to various electrical equipment. For security purposes, it is not a good idea to assign a person who has insufficient knowledge to operate a generator. In case of any repairment, be aware of the voltage that can be life-threatening due to electric shock. Always check the wiring system and the insulating condition of the wiring.
– Engine exhaust gas. The exhaust gas from the engine should be ventilated while the generator is running. Otherwise, it can be harmful to health.
– Fuel tank. Keep it in a safe place. Avoid refueling while the generator is working. Electrical arcs or sparks can ignite fuel.
– Battery. Be aware of gas that occurs from charging and discharging battery. Monitor the level of distilled water in each cell. Always disconnect the negative terminal of the battery first and connect the battery negative terminal at last in order to avoid the arc or short-circuit while tightening the screw.
– Automatic start engine. In case the generator has the Automatic Transfer Switch as a component that automatically starts the engine and supplies the power of the engin, be careful when starting the engine automatically. To avoid such an event, switch off the control unit and disconnect it from the battery terminal when repairing or checking a generator.
– Repair while running a generator. Be careful of rotating parts or parts running at high speeds. The accident can be fetal or cause a loss of organs.
– The connection of the generator should be done in sequence. First, turn off the engine before connecting the cord. Then, check and turn on the engine. When connecting a power cord that has no connector or secure connector, the circuit breaker should be closed while checking the power cord and open the circuit breaker after that.
Transformer is the beginning of power supply to the electrical system. Therefore, it can be considered that the transformer is the heart of the power distribution system. At all stages of the voltage change, the transformer must be used as a pressure regulator to suit any circumstances. Choosing the right transformer to match the needs and necessities and manufacturers or installers assuring the quality of transformer and service, is very important.
In the power supply system, voltage will be converted to higher voltage. For example, 48kV or 24kV to reduce the size of the conductor for supplying electricity over long distances. At the destination before distributing electricity to household, voltage will be converted to 220 V to reduce the danger which may harm the user. For the use of low voltage electrical appliances at 6V or 9V, it will need to convert the home voltage from 220 V to the required voltage. The equipment that performs such functions is called a transformer.
The operation of the transformer is based on the principle of the relationship between electric current and magnetic lines to create the induction force on the conductor. When the current flows through the conductor coil, it will cause magnetic force lines around the conductor. If the input current has size and direction that is changing, it will change the magnetic field as well. If the changed magnetic field passes through the conductor, the induction force will occur on the conductor. The size of the induction force is related to magnetic field strength and the speed of passing through the conductor of the magnetic field.
Switchboard (MDB,EMDB,DB,ATS,MTS) is one of the most important systems in the distribution system. It is responsible for preventing damage, controlling the power supply and receiving electricity from the electrical system, generators or transformer before distributing to organizations that need to use the electricity.
Main Components of switchboard
It is made of metal sheet and is assembled as a cabinet. This may only be opened at front or opened at all sides depending on the design. Its main features are
1. Mechanical properties. Sufficiently support external mechanical strength for normal and non-normal use.
2. Thermal properties. Able to resist the heat from the environment, error in the system and arc from the short circuit.
3. Corrosion resistance properties. Resist to moisture and chemical corrosion. The cabinet also serves to prevent any possible harms which are
a. Prevent the person near the switchboard from touching the exposed parts.
b. Protect the equipment inside the cabinet from external things such as water, solid objects, reptiles, etc.
c. Prevent severe damage from arc that the equipment may fall apart.
The conductor can be made of copper and aluminum. The most commonly used form of busbar is flat form with the rectangular cross-sectional area because it is easy to install and cooled down efficiently. It is divided into 2 types.
1. Naked busbar
2. Coated busbar
Tips for using the busbar
1. The busbar should be placed vertically so it will cool down well.
2. Flat busbar should be placed with no more than 4 bars in parallel. If exceeded, there is a problem with Skin Effect.
3. For coated busbar, coating colors should have a cooling coefficient of about 0.9.
4. Coated busbar has higher conductivity that naked busbar.
5. Red, Yellow, Blue for R, Y, B phase is specified, respectively.
6. The phase arrangement in the switchboard (R, Y, B) should be arranged from the front to the rear of the cabinet, from top to bottom or from left to right.
7. Another phase arrangement is allowed only when connecting to an existing system. However, sign must be marked clearly.
Circuit Breaker for switchboard
For low voltage switchboard, there are 2 types of commonly used breakers which are Air Circuit Breaker and Mold Case Circuit Breakers. Air CB is used as main breakers in high current circuits. Mold Case CB (MCCB) is used for branch circuit or used as a breaker in a small switchboard.
Selection of breakers should consider its width, length, height in order to fit in the board properly, IC currents including co-ordination.
Meter for switchboard
The basic measuring equipment used in the switchboard is voltmeter and ammeter which must be used with Selector Switch to measure the voltage or current in each phase. The voltage rating of the voltmeter ranges from 0-500V. Current rating of ammeter depends on the ratio of the current transformer, such as 100 / 5A.
For large switchboards, there may be P.F. Meter, Watt Meter or Var Meter depending on the board design. Some board may also be equipped with a P.F. Controller to control the power factor in the circuit.
Accessories for Switchboard
There are several components in the switchboard such as
1. Current Transformer (CT) for Switchboard. The device is used to measure current by connecting with the CT ammeter. CT meter used in the market is divided into 2 groups, the ratio of 1 and the ratio of 5. The ratio of 5 is commonly used in the switchboard such as 50/5, 100/5, 300/5, etc. Normally CT will be selected based on the size of the main circuit breaker but must be higher than breaker rating such as 100A main breaker must be used with CT of 100 / 5A. Use caution of CT is not to open the secondary circuit of the CT because it causes high voltage over the coil and cause the CT to burn. If there is no use of CT, the two terminals of the CT should be short circuited.
2. Selector Switch for Switchboard. The Ammeter Selector Switch is used with CT and Panel Ammeter to measure current in the switchboard. The Voltmeter Selector Switch is used with the Panel Voltmeter to measure the switchboard voltage. To connect the circuit, user should check the diagram that comes with the device. Because each brand has different circuit connection.
3. Plot Lamp for switchboard. It is a lamp that indicate the work status and to inform if there is power supplied to the switchboard or not. Pilot Lamp has two types which are.
3.1 with potential transformer
3.2 without potential transformer
The potential transformer will reduce the voltage to suit the voltage of the lamp, such as 220 / 6.3V.
4. Fuse for switchboard. Fuse is a glass tube that used to protect circuit of meter and Pilot Lamp.
5. Busbar insulator for switchboard. It is an insulator for busbar. One side is attached to switchboard while the other side will attach the busbar. There are many types of insulators to fit each types of busbar