Electrical Circuits and Controls for Commercial Gas Appliances 080206c Flashcards
What is a pipe spool drawing?
The use of symbols to simply information and enable you to convey information in a clear and uncluttered manner
What is the most widely used type of schematic?
Ladder diagram
How is the exhaust fan in a direct fired make up air unit proven to be running?
Via interlock switches
What is a relay?
A device that opens or closes a set of electrical contacts and is activated by a coil
What is a contactor?
Works thr same as a relay but is larger
20 amps or larger is usually a contactor. Anything smaller is a relay
What is a coil?
Activates the contacts to either open or close
What is the purpose of an end switch?
Used to verify that a mechanical action has been completed and it is safe for another action to take place by closing or opening an electrical circuit
A high velocity air switch is what kind of switch?
Normally closed opens on pressure drop
How do you find VA?
VA = V x A
What are the 2 main types of gas valves?
Diaphragm and solenoid
What are the main gas valve or relay defined as on a electrical circuit?
Primary control
On a single valve installation, a bleed tube may be vented to an adjacent continuous pilot burner but what provisions must be met?
- bleed flame does not interfere with the safety control system (thermocouple)
- the inlet pressure is 0.5 psig or less
- the fuel is lighter than air
- the tubing material has a melting point in excess of 1450°F
What is a the purpose of a solid state rectifier?
Changes the current from ac to dc and can be used to regulate the speed of a blower motor
What is electrical power measured in?
Watts
How is electromotive force measured?
Volts
How is a voltmeter connected to a circuit?
Paralell power on
How is a ammeter connected to a circuit?
Series power on
How is a ohmeter connected to a circuit?
Paralell power off
What kind of diagram shows how an appliance opperates?
Ladder diagram
What does the ignition module activate first when energized?
Ignition and pilot valve
What will poor ground on an ignition module cause?
No main flame
