Schematic Diagrams – Relay School

What is a one line diagram an overview of?

• The substation

• The control circuits

• The panel wiring

• The drawing revisions

The AC Schematic shows in more detail all three phases and neutral connections of AC voltage and current circuits.

• True

• False

Fill in the blank: The DC Schematic shows in more detail the control circuits including _______, closing, and alarms.

• tripping

• switching

• monitoring

• signaling

What does the panel wiring diagram identify?

• The substation overview

• The actual wiring on a panel

• The control circuits

• The drawing revisions

Utilities may have different methods to identify areas of the drawings that have been revised including _______.

• circling, cross hatching, etc.

• highlighting, underlining, etc.

• color coding, numbering, etc.

• doodling, sketching, etc.

A phasor is a representation of a complex number used in electrical engineering to represent sinusoidal functions.

• A type of resistor

• A representation of a complex number used in electrical engineering

• A unit of frequency

• A type of capacitor

The purpose of using phasor diagrams is to:

• visualize complex numbers in electrical engineering

• measure the speed of light

• calculate gravitational force

• determine chemical reactions

What is the frequency of the United States power system?

• 50 Hz

• 60 Hz

• 70 Hz

• 80 Hz

Refer to the typical balanced 3 phase current waveform and equivalent phasor diagram shown in fig. 2. What is the phase relationship between the currents using the phasor diagram?

• The currents are in phase

• The currents are 120 degrees apart

• The currents are 90 degrees apart

• The currents are 180 degrees apart

In a CT circuit, how can the residual current be found using phasors?

• By measuring the phase difference between current and voltage

• By summing the phasors of all currents

• By calculating the vector sum of all phase currents

• By using the RMS value of the current