Electrical Circuits
Electrical pressure in a circuit?
Voltage
Electrical current that flows in one direction?
Direct Current (DC)
____ is the opposition to the flow of electrons in an electrical circuit?
Resistance
What two voltage levels are typically used in HVAC controls?
Low voltage: 30 VAC or less (commonly 24 VAC)
Line voltage: 120 VAC
Electrical multimeter "nickname"?
Truth Teller
_____
reverses direction of flow at regular
intervals (+/-).
Alternating Current (AC)
______ is at a constant value and stays at this value until it is turned off.
Direct Current
Resistance is measured in ____?
ohms, Ω
What tool is used to measure voltage measure in an electrical control system?
DMM or Digital Multimeter
The number of electrons flowing through a conductor is called?
Current
Most common DC voltages are?
1.5V, 6V, 9V 12V, 24V, 36V and 125V
____ is the most common electrical voltage normally produced by generators creating sine waves.
Alternating Current (AC)
___ creates a magnetic field around a conductor when current flows.
Electromagnetism
Unit of measure of current?
Amperage or Amps
The amount of electrical pressure in a conductor is named.
Volts, Voltage
(2) types of current?
Current may be direct current or
alternating current.
What is Ohm's Law?
Ohm’s law is a formula that
expresses the relationship
between voltage, current, and
resistance in a circuit.
A ____ is a device that steps
up or steps down alternating
current.
Transformer
What is (low voltage) 30 VAC or less (commonly 24 VAC) used for in HVAC Controls? Provide two examples.
1. Power supply of field devices and supervisory devices
2. Used to energize the coil of relays to operate high voltage equipment such as fans, pumps, and compressors?
Ohm’s law expresses the relationship between ___, ___, and ___ in an electrical circuit?
voltage, current, and resistance
Name the three types of electrical circuits?
series,
parallel,
series/parallel combinations.
A ___ is a device that
uses a lower voltage to supply power to equipment / components that require a high voltage to operate.
Relay
What is the difference between direct current (DC) and alternating current (AC)?
Direct current (DC) is current that flows in one direction only.
Alternating current (AC) is current that reverses its direction at regular intervals.
___ omits an audible sound when verifying the integrity of the conductors (wiring) in an electrical circuit?
Continuity
The standard tool used when troubleshooting electrical control systems.
DMM , multimeter