Exam (elaborations)
General Theory Study Prep – Questions With Solutions
- Course
- Institution
General Theory Study Prep – Questions With Solutions
[Show more]
Content preview
General Theory Study Prep – Questions With SolutionsWhat would the power factor be with these readings taken from a single
phase AC inductive circuit (230V - 11A - 2024W) Right Ans - 0.8
P (real/true power in W) / S (apparent power in VA) = P.F
What is the definition of the term impedance as applied to an AC circuit?
Right Ans - The total opposition (in Ohms) to the current flow in an AC circuit.
What is pull-out torque when applied to an AC induction motor? Right Ans
- The maximum value of torque the motor can produce.
What are the two main functions of the ballast in a fluorescent light fitting?
Right Ans - Provide a starting voltage
&
Limit current in the circuit.
What is the maximum resistance for the main earthing conductor? Right
Ans - No more than 0.5 Ohms.
A single-phase low voltage electrical installation has an earth fault loop
impedance of 0.2 Ohms when measured at the switchboard.
Calculate the prospective short circuit current. Right Ans - 1150 A
(230VAC / 0.2 Ohms = 1150 A)
A plug-in electric heater is designed for use on a 230/240 VAC supply.
The heater's resistance reads 26 Ohms when tested at the plug.
What is the supply voltage if the power dissipated is 2035W? Right Ans -
230V
, (2035W / 230VAC = 8.85A)
(2035W / 8.85A = 230VAC)
How does a single-phase AC permanently split capacity motor differ from a
single-phase AC capacitor start motor? Right Ans - It has no centrifugal
switch.
What do the figures AC80KA mean on an HRC fuse cartridge? Right Ans -
Alternating current 80000A maximum that the fuse can safely interrupt.
State the meaning of the term close excess current protection. Right Ans -
Will operate at 1.5 times rating within four hours.
Which single-phase AC induction motor would be best suited for a garage
door opening-closing operation? Right Ans - Permanent split capacitor
motor.
Define the term peak inverse voltage as applied to a semiconductor device.
Right Ans - Maximum voltage the semiconductor device can withstand in
reverse bias.
State the minimum resistance of an electrical installation that does not
contains MIMS heating elements. Right Ans - 1 M Ohms
A 6 pole 50Hz motor has a slip of 5%.
What speed does the motor run? Right Ans - 950 RPM
(60sec x 50Hz = 3000RPM
3000RPM / 3 pairs = 1000RPM
1000RPM x 0.05 = 50%slip
1000RPM - 50%slip = 950RPM).
What does BJT stand for when applied to semiconductors? Right Ans - No-
Polar Junction Transistor.
In what form is the voltage output from a PWM converter? Right Ans - A
series of rectangular pulses.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Zendaya. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79373 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now
