Generator Protection

Generator protection

* Over current protection
* Short circuit current protection
* Earth fault protection
* Differential Current protection
* High voltage Protection
* Under voltage protection
* Under frequency protection
* Over Frequency protection
* Reverse power protection

Mainly Genarator set can be divided into two part

1. Engine
2. Alternator
   

Generator SET

A Generator set has five systems. for a good condition of a generation of electricity, they should maintenance properly.

• Starting System

• Fuel System

• Exhaust air System

• Lubrication oil System

• Cooling System

Earthing System

Panel boards are selling several Countries then earthing systems and main Bus bar arrangement are changed each country.

Type of System Earthing

01. TN system:

TN power system have one point directly earthed, the exposed conductive parts of the installation being connected to that point by protective conductors. Three types of TN systems are recognized, according to the arrangement of neutral and protective conductors,

(a) TN-S System – A system having separate neutral and protective conductors throughout

(b) TN-C-S System – A system in which neutral and protective function are combined in a single conductor in a part of system.

(c) TN-C system - A system in which neutral and protective functions are combined in a single conductor throughout.

02. TT System -

The TT power system has one point directly earthed, the exposed conductive parts of the installation being connected to earth electrodes electrically independent of the earth electrodes of the power system,

03. IT System -

The IT power system has no direct connection between live parts and earth, the exposed conductive parts of the electrical installation being earthed

Panel Designing

Panel designing process we need following details. Because panel is depended in these conditions.

· The "Form Type"

· Degree of protection (IP)

· Panel Colors

· Earthling System

· Short Circuit Time Duration

· Fault Current

And Single line diagram or bill of materials (Number of incoming and outgoing feeders) details.

Types of Compressor

A compressor converts the mechanical energy of an electric or combustion motor into the potential energy of compressed air. Air compressors fall into two main categories Reciprocating and Rotary.

01. Piston type Compressors

02. Screw type Compressors

Emergency stop and mushroom head push button.

There are many types of emergency push button are available.

1) Trigger action push-pull

2) Trigger action turn to release.

3) Trigger action key release

Thermal Overload Relay

Thermal overload relay is a one of the protective device, which protects the load [motor] from overload. There are many sizes are available. Also so many setting ranges are available. This setting time is depends on the rated current of the motor.

It has 3 no of power controlling poles and also has two auxiliary contact points such as normally open and normally closed.

1. Overload protection.
2. Unbalance current tripping protection

UVT COIL

UVT coil (Under Voltage Trip)

UVT coil is normally close point. When de-energized the coil MCCB will be trip. UVT coil is used to detect the phase.

SHUNT COIL

Shunt coil and UVT (Under Voltage Tripping) coil of the MCCB)

How to connect the shunt coil or UVT coil to the MCCB

First trip the MCCB by using manual test button and after connect the UVT or shunt coil to the MCCB.

v Shunt coil

Shunt coil is normally open contact point. When energized the coil the MCCB will be trip.

Protection of the MCB / MCCB

Protection of the MCB / MCCB

MCB	MCCB
1. Short circuit	1.Short circuit
2. Over load	2. Over load
	3. Other protection

Chart 03.04.01

MCB / MCCB has two mechanism to trip

1). Bimetallic part

2). Electromagnetic part

Thermal tripping

This action provides bimetallic part. It is used to protect the circuit from over load.

Electromagnetic tripping

This action provides electromagnetic field. It is used to protect the system from short circuit.

PUSH BUTTON

There are many three types of push buttons are available.

1). Single headed push button, spring return.

2). Double headed push buttons, spring return.

3). Emergency stop and mushroom head push button.

RELAY - Reset mode

Reset mode

We can select two paths to resetting the overload relay.

1. Auto reset mode
2. Manual reset mode.

How to set the setting value of the overload relay

Assumed rated current of the motor is equal to the Ina = 18A

This setting is depends on the rated current of the motor.

RELAY

Feature of the Thermal Overload Relay

1. It has current setting dial. We can adjust the rated current of the motor.
2. It has trip indicator.
3. We can test the TOR (Trip On Not).

When trip the overload relay auxiliary contact point change. Therefore, cut the control circuit.

Feature of the Thermal Overload Relay

1. It has current setting dial. We can adjust the rated current of the motor.
2. It has trip indicator.
3. We can test the TOR (Trip On Not).

When trip the overload relay auxiliary contact point change. Therefore, cut the control circuit.

Utilization category

1) Resistive load

2) Normal motor

3) Transformer

4) Capacitor bank

Types of utilization category.

MOTOR STARTING METHOD

The starting current of 3-phase induction motor is usually 5 to 8 times the full load current or the motor. Therefore, starting when large size induction motor which are used in industry. Their starting current will cause on unacceptable level of voltage drop in the supply lines as a result this sudden voltage drop nearly will also effect the other consumer. Therefore, the supply authorities that when starting large size 3 – phase induction motors the users must adopt some starting method to reduce the starting current. Four methods are used in there.

Starting method

1) Liquid Rheostat

2) Direct on line starting method

3) Star – delta starting method

4) Auto transformer starting method

5) Rotor resistor starting method