Figure 1. The connection between the electrical panel to the loads panel and computer
Figure 1 show the connection between the electrical panel to the loads and computer. From the computer, the RTU programming must be burn out to the ICP-
Controller first, then after finish burn out, run the SCADA programming. The programming will interface automatically.
2.2 Equipments characteristic
In this project, there are eight material that being use including for the hardware and software. For the software material, indusoft and isagraft is use to
determine SCADA and RTU programming. For the hardware, the material that being installed, are miniature circuit breaker MCB, relays, DC power supply, ICP-
Controller, input output module, and bulb. For this project, 1.5mm2 cable size is being use to connect all the equipment.
2.2.1 Miniature Circuit Breaker MCB
All circuit breakers have common features in their operation, although details vary substantially depending on the voltage class, current rating and type of the
circuit breaker. The circuit breaker must detect a fault condition; in low-voltage circuit breakers this is usually done within the breaker enclosure. Large high-voltage
1. Actuator lever - used to manually
trip and reset the circuit breaker. Also indicates the status of the
circuit breaker On or Offtripped. Most breakers are
designed so they can still trip even if the lever is held or locked
in the on position. This is sometimes referred to as free
trip or positive trip operation.
2. Actuator mechanism - forces the
contacts together or apart. 3.
Contacts - Allow current to flow when touching and break the
flow of current when moved apart.
4. Terminals
5. Bimetallic strip
6. Calibration screw - allows the
manufacturer to precisely adjust the trip current of the device after
assembly.
7. Solenoid
8. Arc divider extinguisher
circuit breakers have separate devices to sense an over-current or other faults. Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit;
some mechanically stored energy within the breaker is used to separate the contacts, although some of the energy required may be obtained from the fault current itself.
When a current is interrupted, an arc is generated - this arc must be contained, cooled, and extinguished in a controlled way, so that the gap between the contacts
can again withstand the voltage in the circuit. Finally, once the fault condition has been cleared, the contacts must again be closed to restore power to the interrupted
circuit. A circuit breaker is an automatically-operated electrical switch designed to
protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset
either manually or automatically to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household
appliance up to large switchgear designed to protect high voltage circuits feeding an entire city. [1]
Figure 2. Photo of inside of a circuit breaker
When closing DC circuits, the current reaches about 95 of its final steady state value after time 3τ, where τ is the time constant. Similarly, when an alternating
current is closed, the current reaches a steady value after a transient process. The time depends upon the resistive, inductive and capacitive elements of the circuit. The
highest switching current is achieved if switching is effected at zero voltage very high peak currents can develop if the switch is closed on short circuit conditions.
Below a threshold voltage, any circuit can be opened without any arc formation. In practice, however, the commonly used switches do produce an arc while interrupting
the current. The arc must be either kept limited or extinguished at the earliest in order not to damage the contacts.
Copper is by far the most widely used contact material. But since non-conducting layers are formed on copper contacts as a result of switching, a wiping action is
provided while designing copper contacts. These are also plated with a layer of silver in many applications. In low voltage circuits, silver is also in use as contact material.
Since switching almost invariably gives rise to arcing, extinguishing such arcs assumes vital importance to prolong contact life.
The following methods are employed:
•
Lengthening of the arc till it extinguishes
•
Intensive cooling in jet chambers
•
Division into partial arcs
•
Zero point quenching
•
Connecting capacitors in parallel with contacts in DC circuits
•
Use of vacuum
•
Use of air
•
Use of oil Figure 2.1 Moulde case circuit
breaker MCCB
The contacts need to be kept properly insulated from other metal parts including the body. Different insulating materials are in use. The most commonly used material is
cast epoxy. Besides, PVC, polystyrene, polycarbonate and ceramics are also in use. Figure 2 show the photo of inside of circuit breaker. Small circuit breakers
are either installed directly in equipment, or are arranged in a breaker panel. The 10 ampere DIN rail mounted thermal-magnetic miniature circuit breaker is the most
common style in modern domestic consumer units and commercial electrical distribution boards throughout Europe.
In this project, the function of MCB is to cut off the supply to the load and also to the panel. So it will be easy to do the maintenance or repairing if there any
problem occurred to the system.
2.2.2 Relays
