Whether you want a master electrician, journeyman electrician or electrical contractor’s license you’ll need to know how to answer theory related calculation questions to pass your exam. The formulas you’ll need to answer these types of questions may not be referenced in your code book.
How would you answer the following question:
What is the horsepower rating for a 208-volt three-phase induction type motor with and efficiency rating of 80%, a power factor of .85 and a current rating of 30 amps?
Solution:
Step #1
Identify the Hp formula required when the voltage, amperage, efficiency and power factor are known.
Hp = I x E x 1.732 x Eff x Pf/746 watts*
*746 watts = 1 Hp
Step #2
Plug known values provided in the question into the formula.
Hp = 30 amps x 208 volts x 1.732 x .80 x .85/746 watts
Step #3
Solve the equation.
Hp = 30 amps x 208 volts x 1.732 x .80 x .85/746 watts
Hp = 9.85
Preparation is the key to being able to answer these kinds of questions quickly and easily. We’ll help you to understand exam question terminology and develop the test taking skills you’ll need to succeed. Call 888-919-3926 to start preparing to pass your exam today.