Table of Contents
- 1 Why are grounding straps required on resilient mounted motors?
- 2 What type of motor is most commonly used in Hvacr applications today why?
- 3 Why do some motors have a different insulation class than others?
- 4 When reading resistance from a motor terminal to the motor shell ground what does a very low resistance reading mean?
- 5 What is the purpose of the legend on Hvacr electrical diagrams?
Why are grounding straps required on resilient mounted motors?
A belt-driven blower assembly that has a resilient mounting requires a grounding strap. Why? Because it is electronically “isolated” from any grounded metal by rubber, and can become electronically hot because so.
Why do motors mounted on resilient rubber mounts require a ground wire from the motor to the frame quizlet?
Why must resilient-mount motors have a ground strap? A resilient-mount motor is electrically and mechanically isolated from the metal frame by rubber. If the motor were to have a ground (circuit from the hot line to the frame of the motor), the motor frame would be electrically hot w/ out the ground strap.
What type of motor is most commonly used in Hvacr applications today why?
What type of motor is most commonly used in HVACR applications today? Why? PSC motors. They have a 65% efficiency rating and a low starting torque.
Do motor bearings require yearly lubrication?
A drip-proof motor is designed to prevent any lubricating oil from leaving any of the bearings. Regardless of the type of motor or application, the motor bearings require yearly lubrication.
Why do some motors have a different insulation class than others?
The permitted temperature rise of the windings of an electric motor are subdivided into different insulation classes and temperature limits. The above table applies to motors in an ambient temperature up to 40°C and an altitude of less than 1000 meters above sea level.
Why motor winding is failure?
Winding single-phased (delta-connected) A single-phased winding failure is the result of an open in one phase of the power supply to the motor. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections.
When reading resistance from a motor terminal to the motor shell ground what does a very low resistance reading mean?
Which of the statements is correct? Technician “A” says that while checking the windings of a compressor, a reading of 10 ohms or less from the common terminal to ground indicates that the motor is okay.
What is the most common type motor used in residential and light commercial system?
In residential and light commercial HVAC, we work primarily with PSC (permanent split capacitor) motors. However, it is good to be aware of some other types. A common medium torque single phase motor with a run capacitor always in the circuit.
What is the purpose of the legend on Hvacr electrical diagrams?
What is the purpose of the legend on HVAC/R electrical diagrams? A source of power, a load, and a path for the current to flow. Is used to locate actual parts and connections within the unit itself. How are control devices wired in most HVAC circuits?
Why do many starters have manual resets?
Define a motor starter. Why do many starters have manual resets? so the technician can reset it by hand. What causes the overload of a starter to open and disable the power circuit?