Commercial and Industrial Electrical Systems is a comprehensive coverage on every aspect of design, installation, testing and commissioning of electrical systems for residential, commercial and industrial buildings.
For a electrical system to perform according to industrial standard the engineers or technician working on the electrical system must understand pertinent aspect of network and installation of electrical system from project procedures, rules and standard to design principle and installation practice. It is therefore imperative that the drafters and designers must consider the process and load data.
PROCESS AND LOAD DATA
§Process and load data are compiled in form of an electrical load summary. The data used in compiling the electrical load summary are extracted from the equipment which is list jointly prepared by the process and mechanical groups, while detailed information on the mode of supply are picked from the P&ID.
§ Definition – Load Summary
A detailed listing of all load to be served by the electrical distribution system. It is used to determine the power requirements of the system in order to properly size power sources, distribution equipment, and feeder systems. The load summary also aids in determining system voltages.
Components of a Load Summary
Definition – Running load
The actual electrical load of the facility during operation. Running load is used to size the utility service, generators, transformers, feeders, motor control centers, circuit breakers, and UPS
Components of a Running load
nContinuous load – loads expected to operate without stopping for 3 hours or more
nIntermittent load – loads expected to operate without stopping for periods less than 3 hours or more
nSpare load – loads which operate only when other loads are not operating
Definition - Peak load
The maximum instantaneous load drawn by a system during a specified period of time. It is obtained when the when the facility is operating at full capacity and the maximum instantaneous load is energized.
Definition - Stand-by loads
Critical loads that may cause damage to process or product if power is interrupted.
Definition - Emergency loads
Loads deemed essential for personnel safety and UPS loads
Correction factors applied in summing the total consumed load vary from one organization to the other.
Assume the following for this training only
Continuous load (C) 100%
Intermittent load (I) 30%
Standby load (S) 0%
From the above factors
Running load = C+ 30%I
Peak load = C + I