UNDERSTANDING ELECTRICAL LOAD SCHEDULE

The electrical load schedule is an estimate of the instantaneous electrical loads operating in a facility, in terms of active, reactive and apparent power (measured in kW, kVAR and kVA respectively). The load schedule is usually categorized by switchboard or occasionally by sub-facility / area.

This video explains in detail the steps to be followed for the calculating the Electrical load schedule.
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Electrical Load List can be defined as a document (electrical) that embodies the total electrical load within the plant along with the distribution feeders. It is used to determine the amount of power required for an installation in terms of active, reactive, and apparent power (measured in kW, kVAR and kVA respectively). A Load schedule is usually categorized by Switchboard or by Sub-facility/Area.
Electrical load Schedule Calculation is carried out to properly size Electrical Equipment, conductors and determine the protection and control systems.

Electrical Load schedule should be started as soon as practically possible. The calculation can be started with a preliminary key single line diagram and any preliminary details of process/ building/ facility loads. This load schedule will give an early estimate of the total power consumption. From this the number of generators and utility intake can be estimated.

The basic steps which are followed when creating the load schedule are as given below:
STEP 1: Collect list of expected electrical loads in the facility
STEP 2: For each load, collect the electrical parameters, e.g. nominal / absorbed ratings, power factor, efficiency, etc.
STEP 3: Classify each load in terms of Switchboard, load duty and load criticality
STEP 4: For each load, calculate the expected consumed load
STEP 5: For each switchboard and overall system, calculate Operating & Peak Loads

Operating Load (OL) or the Total Plant Running Load (TPRL) is the expected load during normal operation.
As can be seen from the formula, Operating load is calculated as sum of 100% of all the Continuous loads + 30% of the Intermittent loads.

Peak Load (PL) or the Total Plant Peak Load (TPPL) is the expected maximum load during normal operation. Peak loading is typically infrequent and of short duration, occurring when standby loads are operated (e.g. for changeover of redundant machines, testing of safety equipment, etc.).
Peak load is calculated as sum of 100% of all the Continuous loads + 30% of the Intermittent loads + 10% of the standby loads.