How do you calculate lighting loads?

To calculate the lighting load, we use this formula: Watts = Volts * Amps (or W=VA in short). In most cases, you’ll get two of these three elements. That means that your household has a lighting load of 4800W.

How is contactor calculated?

As per above chart:

1. Type of Contactor = AC7b.
2. Size of Main Contactor = 100%X Full Load Current (Line).
3. Size of Main Contactor = 100%x6 = 6 Amp.
4. Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line).
5. Making/Breaking Capacity of Contactor = 8×6 = 52 Amp.

What is the formula for calculating electrical load?

Calculating an Electrical Load in a Simple Circuit Let Power = Voltage * Current (P=VI). Let Current = Voltage/Resistance (I=V/R). Apply Kirchoff’s Second Law, that the sum of the voltages around a circuit is zero. Conclude that the load voltage around the simple circuit must be 9 volts.

What is a lighting contactor?

Lighting contactors are relay switches that control the flow of electricity through a circuit powering the lighting in a given area. A lighting contactor switch operates at a lower but safer load and controls the high voltage/current circuit using an electromagnet. Turn the power off for the entire system.

What does the code state for how much power is needed to run general lighting loads in dwelling?

The general calculated load must be at least 100% for the first 10kVA, plus 40% of the remainder of the following loads: General lighting and receptacles: 3VA per sq ft. Small-appliance and laundry branch circuits: 1,500VA for each 20A, 120V small-appliance and laundry branch circuit specified in 220.52.

What are the possible load for lighting load?

Calculating Maximum Load Multiply the amp number by the voltage. In the case of a 15-amp circuit at 120 volts, the formula would look like this: W = 120 x 15. The result is W = 1,800, so 1,800 watts is your maximum power load.

How do you size a compressor contactor?

If the compressor is not listed in the table the contactor can always be sized for full voltage starting by selecting a contactor of the next amperage rating larger than the compressors Rated Load Amps (RLA) and then checking the LRA requirements against the rating of the chosen contactor.

How do you calculate structural load?

Dead Load Calculation for a Building Dead load = volume of member x unit weight of materials. By calculating the volume of each member and multiplying by the unit weight of the materials from which it is composed, an accurate dead load can be determined for each component.

How long can a contactor stay on?

For example, a properly applied contactor will have a life span of 10,000 to 100,000 operations when run under power; which is significantly less than the mechanical (non-powered) life of the same device which can be in excess of 20 million operations.

What causes contactors to fail?

Contactors fail due to a wide range of reasons. Some of the common reasons are excess current flowing through the contacts. High current can be either due to overload or due to short-circuit. High current can cause the contacts to melt.

How to calculate the size of a contactor?

When the starter switches over to Delta, the motor draws full power, but since the contactors and the overload relay are usually wired within the Delta, you need to use contcators and relay which are only rated 1/√3 =58% of the full rated power of the motor. Making/Breaking Capacity of Contactor= Value above Chart x Full Load Current (Line).

When do you use a lighting contactor in a motor?

When someone uses a lighting contactor in a motor application, that’s a misapplication. The same is true when someone uses a “normal operation” motor contactor for motor jogging duty. Contactors have specific designs for specific purposes.

What are the different types of contactors rated?

Contactors are rated by designed load current per contact (pole),maximum fault withstand current, duty cycle, voltage, and coil voltage.

When do you use a normal operation contactor?

The same is true when someone uses a “normal operation” motor contactor for motor jogging duty. Contactors have specific designs for specific purposes. When selecting contactors, you’ll use one of two common standards: NEMA or IEC. Both match a contactor with the job it has to do, but they do so in different ways.