SINGLE-LINE AND BLOCK DIAGRAM

SINGLE LINE DIAGRAM

The single-line diagram is circuit diagram where “one-line” is shown to represent three phrase of a three phase power system. Single-line diagram are often found showing major switching and switchgear design.

The single-line diagram provides the following information

1. Manufacturers type designations and ratings of devices
2. Ratio of current and power transformers,taps to be used in multi-ratio transformers, and connections of double-ratio transformers
3. Function of relays
4. The sizes, type, and number of incoming and outgoing cables
5. Switch and fuse ratings in volts and amperes
6. Circuit breaker ratings in volts and amperes
7. Rating connections of wye and delta power transformer windings
8. The interrupting rating, type, and number of trip coils on circuit breakers
9. Metered points and type of metering
10. The amount of the load on all feeders

BLOCK DIAGRAM

A block diagram represents the major functional parts of complex electronic and electrical systems by blocks.

Example of Block Diagram

There are two major differences between the single-line diagram and the block diagram.

1. The single-line diagram uses symbols, rather than labeled blocks, to represent components
2. The single-line diagram shows all components in a single line, there are no interconnections shown for selected components as were shown on the block diagram (for example,alternator to voltage regulator and back to the battery).

Source :

Petruzella,Frank D. 1996. Industrial Electronics. Singapore : McGraw Hill

http://www.myodesie.com/index.php/wiki/index/returnEntry/id/3027

http://kb.gbb.co.in/question/single-line-diagramsld/

http://electriciantraining.tpub.com/14176/css/14176_103.htm

 

 

SAFETY IN THE WORKPLACE

Safety has become an important factor that must be paid attention in the working environment. A safe operation depends largely upon all plant personnel being informed and aware of potential hazards. Here some of accident prevention signs that must be obeyed by the worker.

What is personal protective equipment?

Personal protective equipment, commonly referred to as “PPE”, is equipment worn to minimize exposure to serious workplace injuries and illnesses.

Types of Personal Protective Equipment

PPE can be considered in the following categories, based on the type of protection afforded by the equipment:

• Respiratory protection – for example, disposable, cartridge, air line, half or full face
• Eye protection – for example, spectacles/goggles, shields, visors
• Hearing protection – for example, ear muffs and plugs
• Hand protection – for example, gloves and barrier creams
• Foot protection – for example, shoes/boots
• Head protection – for example, helmets, caps, hoods, hats
• Working from heights – for example, harness and fall arrest devices
• Skin protection – for example, hats, sunburn cream, long sleeved clothes
• Other personal protective equipment: This may include PPE for specific tasks such disposable clothing for working with chemicals, radiation hazards, welding, painting. Examples include: lead aprons for x-ray protection; sleeve protectors, aprons, coveralls when using chemicals; leather jackets, trousers and spats for welding; thermal and cold protective clothing for work near furnaces and cool rooms.

In 1970, Congress created a regulatory agency known as the Occupational Safety and Health Administration (OSHA). OSHA sets standards that regulate safety in plants. The following colors have been established by OSHA to designate certain cautions and dangers:

• RED : is used to designate fire protection equipment, portable containers of flammable liquids, emergency stop buttons and switches
• Yellow : is used to designate caution and physical hazards
• Orange : is used to designate dangerous parts of machines
• Purple : is used to designate radiation hazards
• Green : is used to designate safety, locations of first-aid

The clothing worn at work is important for personal safety. The following points about appropriate attire that should be worn for each particular job site and work activity.

• Hard hats, safety shoes, and googles
• Safety earmuffs
• Fit Clothing
• Avoid metal jewelry, such as gold and silver
• Long hair should be confined or kept trimmed