Electrical Load Classification
Each Electrical Load may be classified into several different categories for example,
Vital
Essential
Non-essential
Different companies often use their own terminology / terms such as emergency, normal, unmanned and manned operation. In general, there are three ways of considering a load or group of loads.
Vital Loads - Safety of personnel or cause serious damage within the plant if loss of power.
Essential Loads - Loss of the manufactured product (Production @ Economy) if loss of power.
Non-Essential Loads - No effect on safety or production if loss of power.
A vital service is, by definition, a safety matter. Complete redundant of the energy source is required. Vital loads are normally fed from a switchboard /MCC that has one or more dedicated generators and one or more incoming feeders from an upstream switchboard/MCC. These back-up/emergency generators will provide power during the emergency when the main source of power fails. These generators are usually called driven by diesel engines or other generators like TEG, Solar and MTG.
The total power for vital loads is normally small compared to the normal load . The vital load is fed from uninterruptible power supplies (UPS), as AC or DC depending upon the functions needed.
Example of Vital AC Loads
Boiler feedwater supply system
Life support systems
UPS supplies
Emergency lighting and escape lighting
Emergency generator auxiliaries
Helicopter pad lighting
Control room supplies
Vital LV pumps
Example of Vital DC loads
Public address system
Plant alarm systems
System shutdown system
Telemetry systems
Emergency radio supplies
Fire and gas detection system
Navigation aids
An essential supply is, by definition, an economic matter. Therefore the economics of partial or complete duplication of the energy source, of the lines of supply or of the equipment, or the introduction of automatic restarting or changeover facilities etc., shall be evaluated in relation to the consequences of service interruptions.
Example of Essential AC loads
Diesel fuel transfer pumps
Main generator auxiliaries
Main compressor auxiliaries
Main pump auxiliaries
Diesel fire pump auxiliaries
Electric fire pumps
Living quarters
Air compressor
General service water pumps
Fresh water pumps
Equipment room HVAC supplies
Life boat davits
Anti-condensation heaters in
panels and switchboards
Security lighting supplies
Control room supplies
UPS supplies
Radio supplies
Computer supplies
Battery chargers for engine
starting systems
Instrumentation supplies
Example of Non-essential service
Power and lighting supplies to offices, warehouses, residential areas, etc.
All of the vital, essential and non-essential loads can be divided into typically three duty categories:
Continuous duty.
Intermittent duty.
Standby duty (those that are not out of service).
Source: http://www.poweroilandgas.com/2011/07/electrical-load-classification.html
Langganan:
Postingan (Atom)
