Flashcards
06 Handout 1
Cards in this deck (39)
- 1they are used everywhere that electrical or electronic circuits are used. These devices are used to "turn on" or "turn off" current flow in an electrical circuit. These are needed to start, stop, or redirect current flow in an electrical circuit. In its simplest form, is the application and removal of power.Circuit control devices
- 2is the most common circuit control device. They are usually have two or more sets of contacts.switch
- 3Opening these contacts is called "__" or "__" the circuit"break" or "open"
- 4Closing the contacts is called "__" or "__" the circuit."make" or "completing"
- 5This are also used to indicate an open or closed path of current flow. Variations of this symbol are used to represent limit switches, foot switches , pressure switches, level switches, temperature-actuated switches, flow switches, and selector switches. Switches, like contacts, require another device or action to change their state.Switch Symbols
- 6Types of SwitchesManual Switch
Automatic Switch
Multicontact Switches - 7is a switch that is controlled by a person. In other words, it is a switch that you turn on or off. Examples switches are a light switch, the ignition switch on a motor vehicle, or the channel selector on a television.Manual Switch
- 8is a switch that is controlled by a mechanical or electrical device. You do not have to turn this switch on or off.Automatic Switch
- 9The __ will turn a furnace or air conditioner on or off by responding to the temperature in a room.thermostat
- 10The __ electrically turns on the spark plug circuit at the proper time by responding to the mechanical rotation of a shaft.distributor
- 11they are sometimes used to control more than one circuit or to select one of several possible circuits.Multicontact Switches
- 12Kinds of SwitchesSingle Pole Single Throw (SPST)
Single Pole Double Throw (SPDT)
Momentary Contact Multiple Pole Multiple Throw (MPMT or Gang Switch)
Time Delay Switch
Flasher
Rotary Switch
Wafer Switch - 13refer to the number of input circuit terminals.Poles
- 14refer to the number of output circuit terminals.Throws
- 15The simplest type of switch is a "hinged pawl" or "knife blade" switch. It either "completes" (turn on) or "breaks" (turn off) the circuit in a single circuit. This switch has a one input rod and a one output toss.Single Pole Single Throw (SPST)
- 16it has one wire going in it and two wires coming out. The switch sends current to either the high-beams or low- beams of the headlight circuit.Single Pole Double Throw (SPDT)
- 17It is also known as "gang" switches, have movable contacts, which are wired in parallel. These switches move together to supply different sets of output contacts with the current.Momentary Contact Multiple Pole Multiple Throw (MPMT or Gang Switch)
- 18It is made of a sealed capsule that is partially filled with mercury. At one end of the capsule are two electrical contacts. As the switch is rotated (moved from true vertical), the mercury flows to the opposite end of the capsule with the contacts, completing the circuit.Mercury Temperature (Bimetal) Time Delay Flasher
- 19It contains a bimetal strip, contacts, and a heating element. It is normally closed. As current flows through the switch, current flows through the heating element, causing it to heat, which causes the bimetal strip to bend and open the contacts. As current continues to flow through the heating element, the bimetal strip is kept hot, keeping the switch contacts open.Time Delay Switch
- 20It operates basically the same as the time delay switch; except when the contacts open, the current stops flowing through the heating element. This causes the heating element and bimetal strip to cool. The bimetal strip returns to the rest position, which closes the contacts, allowing current to flow through the contacts and heating element again. This cycle repeats over and over until power to it is eliminated.Flasher
- 21It is a multi-contact switch with contacts arranged in a circular or semicircular manner. It is a mid-contact switch part of the schematic with the contacts arranged in a full or partial circle. Instead of a pushbutton or toggle, the mechanism used to select the contact moves in a circular motion and must be turned. Rotary switches can be manual or automatic switchesRotary Switch
- 22It is a rotary switch in which the contacts are on wafers. The wafers are mechanically connected by the shaft of the switch. The schematic of the wafer is always drawn to represent the wafer as it would look if viewed from opposite the operating handle or mechanism.Wafer Switch
- 23It is an electromagnetic switch that converts current flow into mechanical movement. While it is a control device, itself is energized by some other control device such as a switch or a relay. One of the distinct advantages of the use of this is that a mechanical movement can be accomplished at a considerable distance from the control device. The only link necessary between the control device and the __ is the electrical wiring for the coil current.solenoid
- 24Pulling Type Operation Push/Pull TypeSolenoid Operations
- 25As current flows through the winding, a magnetic field is created. If an iron core is placed near the coil that has current flowing through it, the magnetic field will stretch out like a rubber band, reaching out and pulling the iron bar into the center of the coil.Pulling Type Operation
- 26In a "push-pull" type solenoid, a permanent magnet is used for the core. Since "like" magnetic charges repel and "unlike" magnetic charges attract, by changing the direction of current flow through the coil, the core is either "pulled in" or "pushed out." A common use for this type of solenoid is on electric door locks.Push/Pull Type
- 27is simply a remote-control switch, which uses a small amount of current to control a large amount of current. It contains an iron core, electromagnetic coil, and an armature (moveable contact set). This device acts upon the same fundamental principle as the solenoid. The difference between it and a solenoid is that a relay does not have a movable core (plunger) while the solenoid does.relay
- 28are called CONTACTORS; control relays are usually known simply as relays. The function ofthis is to use a relatively small amount of electrical power to control the switching of a large amount of power.Power relays
- 29as their name implies, are frequently used in the control of low power circuits or other relays, although they also have many other uses. In automatic relay circuits, a small electric signal may set off a chain reaction of successively acting relays, which then perform various functions.Control relays
- 30Relay Operation• Current flows through the control coil, which is wrapped around an iron core.
• The iron core intensifies the magnetic field. The magnetic field attracts the upper contact arm and pulls it down, closing the contacts and allowing power from the power source to go to the load.
• When the coil is not energized, the contacts are open, and no power goes to the load.
• When the control circuit switch is closed, however, current flows to the relay and energizes the coil.
• The resulting magnetic field pulls the armature down, closing the
contacts and allowing power to the load. - 31Relay Contact FormsForm A "MAKE
Form B "BREAK"
Form C "BREAK-MAKE"
Form D "MAKE-BEFORE-BREAK"
FORM E "BREAK-MAKE-BEFORE-BREAK" - 32As the circuit is energized,it is pulled to the magnetic coil. This physical movement of the armature of the __ forces the pushrod and movable contacts upward. Any number of sets of contacts may be built onto the relay; thus, it is possible to control many different circuits at the same time. This type of relay can be a source of trouble because the motion of the __ armature does not necessarily assure movement of all the movable contacts.Clapper Relay
- 33This relay is constructed to produce a delayed action when energized. Its operation depends on the thermal action of a bimetallic element like that used in a thermal circuit breaker. A heateris mounted around or near the element. The movable contact is mounted on the element itself. As the heat causes the element to bend (because of the different thermal expansion rates), the contacts close.Thermal Time-delay Relay
- 34It the power dissipated in the load. It has been shown that the power dissipated in the load drops to one-fourth when the current is halved. This is to be expected since power varies as the square of the current. There are two connection variable resistors configured to provide any resistive value within their ohmic range to control the flow of current through them. They are large high wattage, wire-wound variable resistors used in high current applications as the main advantage of this is their higher power rating.Rheostat
- 35is a four-layer solid state current- controlling device. They are mainly used in electronic devices that require control of high voltage and power. This makes them applicable in medium and high AC power operations such as motor control function. This conducts when a gate pulse is applied to it, just like a diode. It has four layers of semiconductors that form two structures, namely: NPNP or PNPN.silicon-controlled rectifier or semiconductor-controlled rectifier
- 36SCR OperationOFF state forward-blocking mode
ON state conducting mode -
Reverse blocking - 37The anode is assigned a positive voltage, the gate is assigned a zero- voltage disconnected, and the cathode is assigned a negative voltage. As a result, Junctions J1 and J3 are in forward bias while J2 is in reverse bias. J2 reaches its breakdown avalanche value and starts to conduct. Below this value, the resistance of J1 is significantly high and is thus said to be in the off state.OFF state forward-blocking mode
- 38An SCR is brought to this state either by increasing the potential difference between the anode and cathode above the avalanche voltage or by applying a positive signal at the gate. Immediately the SCR starts to conduct, the gate voltage is no longer needed to maintain the ON state and is, therefore, switched off by − Decreasing the current flow through it to the lowest value called holding current Using a transistor placed across the junction.ON state conducting mode
- 39This compensates for the drop in forward voltage. This is sincea low doped region in P1 is needed. It is important to note that the voltage ratings of forward and reverse blocking are equal.Reverse blocking
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- hard Fundamentals of Mixed Signals and Sensors Flashcards on 06 Handout 1, created by Eljin Aguilar on 26/11/2024.
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