Electricity And Controls For Hvac R Pdf Output
The purpose of this Info-Tec is to help you understand the fundamentals of electrical systems. Many problems encountered in service work are electrical problems or related to electrical problems.
Electricity And Controls For Hvac R Pdf Output. A company logo to go on the cover page can be added to your reports by placing a file with your logo in the forms folder. 224 Chapter 7 Basic Electricity and Motor Controls In order to develop a basic understanding of how electrical equipment and motor controls work, we need to review. PDF Courses; Electrical. Programs and to provide functional control for a terminal or a piece of HVAC&R. Output points are the control signals. Wondershare Dr Fone Download.
There are two types of electrical current in common use today: alternating current (AC), and direct current (DC). AC current is produced by all electric utilities. AC is very 'flexible'.
Its voltage can be easily stepped up or down by transformers. AC can be converted to DC for final use through rectifiers or solid-state devices. DC current flows always in the same direction. Folx Pro For Mac Cracks. AC current flows first in one direction, then reverses and flows in the opposite direction. The current flow 'alternates', hence alternating current. When AC changes direction, it does not jump from full value in one direction to full value in the other direction. It builds up gradually to maximum, drops off gradually to zero, then repeats this in the opposite direction.
See Figure 1. One of the periods of buildup and back to zero in one direction of flow is an alternation. Two alternations, one in one direction and one in the opposite direction is a cycle. AC current in this country is generated at 60 cycles per second. Older equipment will be identified in cycles (CY) and newer equipment in Hertz (HZ).
CY and HZ mean the same thing. (The CY was changed to HZ to honor a German physicist, Heinrich Hertz, who unraveled the mystery of cycles in AC current.) Electricity has two characteristics: 1. Also called 'potential' or electro-motive force (EMF). It is the 'pressure' of electricity.
Electricity does not have to be flowing to have voltage. If a voltmeter is connected to a 'live' circuit, it will show voltage whether the circuit is connected to a load or not. This can be compared to water in a pipe and a pressure gauge. Voltage is the measure of electrical 'pressure' or potential.
This is the 'rate of flow' of the current. It's the 'gallons per minute'. If water is flowing in a pipe, there is resistance to its flow. There will be a pressure drop from one end of the pipe to the other, depending on the size of the pipe, length of the pipe, and the flow rate. The same situation applies to electricity. Wire offers resistance.
The smaller the wire, the longer it is, the amount of electricity (AMPS) it is carrying all determine the pressure drop, or in electrical terms, voltage drop. Another German Physicist, G.S. Ohms, developed a formula known as 'Ohms Law'.
He found that voltage is the product of amperes and ohms (resistance measure he named after himself) in a resistive circuit. Symbols were established to describe these values. Liton Lvc9016g Manualidades. E for voltage, I for current, and R for resistance. Therefore, voltage equals amperes times ohms: E = I x R. This is a cornerstone formula on which knowledge of electricity is built.