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Relay
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What is air break switch?
An air break switch comprising one or more fixed contacts and one or more movable contacts which are movable between open and closed positions, and a coil which, preferably in conjunction with magnetically susceptible material acting as a flux director, provides a magnetic field in the vicinity of the separable contacts in a direction which is substantially normal to a shock front which tends to be set up by establishment of an arc between the separable contacts and has a value such as to cause the Alfven speed, at least in the vicinity of plasma associated with the arc, to be significantly in excess of the air speed attainable by such shock front, in order to hinder or prevent establishment of such shock front. The coil may surround an arc chamber containing runners defining chutes into which the arc moves under the normal blow-out magnetic field set up by the current through the contacts and in the arc.
What is an overloaded circuit?
An overloaded circuit is an electric circuit that is carrying more current than it is designed to handle, creating a danger of fire through overheating. This often occurs when too many appliances are connected to a circuit at one time.
Does a star delta timer rely on the breaking of the retaining contacts on the star contactor side?
The N.C. (timed open) contacts in the star delta timer energize the star contactor's coil when the system is energized. At the same instant the system is energized, the timer starts to time down the required time which lets the motor get up to speed in the star configuration. When the timer reaches the set point time, a second set of N.O. (timed closed) contacts close the delta contactor's coil and open the N.C. timed contacts of star contactor's coil. The motor now runs in the delta configuration. When the system is de energized the timer contact's reset to its de energized state.
If 120V is present on a120V relay coil what will the voltage reading be across the closed set of relay contacts on a 120V circuit?
0v The relay is designed to act as a switch when voltage is applied across the coil. The contacts open or close but only pass through whatever is connected to those terminals. <<>> When a relay coil is energized the relay's contact change status. The closed set of contacts will open. The 120 volt circuit that is connected will turn off. As to the voltage at the contact terminals, it depends on where you are taking the voltage reading from and to. On the source side of the terminal there will be a reading of 120 volts to neutral or ground. On the other side of the contact terminal there will be zero volts to the neutral or ground. This is because that wire is in series with the load to neutral. A meter reading across the relay terminals will read 120 volts.
What is close contact relay?
A relay is an electrical switch. It consists of a electromagnetic coil and a set of mechanical contacts. Depending on the relay their could be multiple sets of mechanical contacts. The close contact lets current flow through the mechanical contacts when the relay is not turned on. When the relay is turned on current flow is stopped. This is called a normally closed contact or NC The open contact works the opposite of the closed and is referred to as a normally open contact or NO
What is interposing relay?
It is a relay that has two states. in one state a set of contacts will make or break. In the other state the other set of contacts will make or break. One coil operating two sets of common, normally open, normally closed. each set of contacts will change states when the coil is momentarily energized.
A device that opens and closes a set of contacts when its coil is energize?
The device is a relay. A relay may have several sets of contacts, or sets of open and closed contacts that "change state" as the coil is energized.Changing state means that the normally open contact will close and the normally closed contact will open when the coil is energized.
What is air break switch?
An air break switch comprising one or more fixed contacts and one or more movable contacts which are movable between open and closed positions, and a coil which, preferably in conjunction with magnetically susceptible material acting as a flux director, provides a magnetic field in the vicinity of the separable contacts in a direction which is substantially normal to a shock front which tends to be set up by establishment of an arc between the separable contacts and has a value such as to cause the Alfven speed, at least in the vicinity of plasma associated with the arc, to be significantly in excess of the air speed attainable by such shock front, in order to hinder or prevent establishment of such shock front. The coil may surround an arc chamber containing runners defining chutes into which the arc moves under the normal blow-out magnetic field set up by the current through the contacts and in the arc.
How does an ice cube relay work?
The relay is used to "interlock" a circuit. It consists of a coil and a number of auxiliary "normally open" or "normally closed" contacts. A limiting condition is wired through the coil contacts and resulting conditions are wired through the auxiliary contacts. When the limiting condition is met, the coil will pull in and change the state of the auxiliary contacts. For example, if you want a lamp (lamp 1) to turn off when a second lamp (lamp 2) is turned on, lamp 1 would be wired through a "normally closed" set of contacts and lamp 2 would be wired through the coil contacts. When lamp 2 is turned on, the coil will pull in and open the "normally closed" contact for lamp 1, turning it off.
Does a shunt trip breaker work from a dry set of contacts?
Yes, but you need a power source, for the shunt trip coil voltage, in the circuit.
What is an overloaded circuit?
An overloaded circuit is an electric circuit that is carrying more current than it is designed to handle, creating a danger of fire through overheating. This often occurs when too many appliances are connected to a circuit at one time.
When there is a change in the magnetic field in a closed loop of wire?
This can be done by moving a magnet through a coil of wire. This is called electromagnetic induction and it results in a voltage being induced in the coil. The charges in the coil are set in motion...
What is magnetic motive force?
mmf is which sets up or tends to set up the magnetic flux in magnetic circuitNote. The term is magnetomotive force, notmagnetic motive force. For a coil, the magnetomotive force is the product of the current flowing in that coil and the number of turns, and is measured in amperes (A), although it is often spoken as 'ampere turns', to avoid any confusion with current.
Does a star delta timer rely on the breaking of the retaining contacts on the star contactor side?
The N.C. (timed open) contacts in the star delta timer energize the star contactor's coil when the system is energized. At the same instant the system is energized, the timer starts to time down the required time which lets the motor get up to speed in the star configuration. When the timer reaches the set point time, a second set of N.O. (timed closed) contacts close the delta contactor's coil and open the N.C. timed contacts of star contactor's coil. The motor now runs in the delta configuration. When the system is de energized the timer contact's reset to its de energized state.
What are the different ways to induce current in a coil?
Different ways to induce current in a coil are as given below:(1) If a magnetic field is changed round a coil then an induced current is set up in the coil. It can be done by taking a bar magnet and bringing it closer to the coil or taking it away from the coil.(2) If a coil is moved in a magnetic field, then again an induced current is set up in the coil.(3) If a coil is rotated in a uniform magnetic field, it may also cause an induced current in the coil.(4) If we take two coils and insert them over a non conducting cylindrical roll then on changing current flowing in one coil, an induced current is obtained in the other coil.CommentYou don't induce a 'current' into a coil; you induce a voltage. If that coil is open circuited, then no current will flow. If, on the other hand, the coil is connected to a load, or its opposite ends short-circuited, then the induced voltage will cause a current to flow. Remember, current will only flow if there is a load, or short circuit, and the value of the current will depend upon the value of the induced voltage and the resistance of the load or short circuit.
What are two ways to cause a current in a wire coil?
Different ways to induce current in a coil are as given below:(1) If a magnetic field is changed round a coil then an induced current is set up in the coil. It can be done by taking a bar magnet and bringing it closer to the coil or taking it away from the coil.(2) If a coil is moved in a magnetic field, then again an induced current is set up in the coil.(3) If a coil is rotated in a uniform magnetic field, it may also cause an induced current in the coil.(4) If we take two coils and insert them over a non conducting cylindrical roll then on changing current flowing in one coil, an induced current is obtained in the other coil.CommentYou don't induce a 'current' into a coil; you induce a voltage. If that coil is open circuited, then no current will flow. If, on the other hand, the coil is connected to a load, or its opposite ends short-circuited, then the induced voltage will cause a current to flow. Remember, current will only flow if there is a load, or short circuit, and the value of the current will depend upon the value of the induced voltage and the resistance of the load or short circuit.
How would you explain in short the working of a DC motor?
A simple DC motor, like one in a motorized remote control (RC) vehicle, works on a simple electromagnetic principle. The idea is that if you can generate a magnetic field in a coil on a rotor by applying a voltage, and you can set this field up to "buck" against a fixed magnetic field in the case or stator of a device, you can get the applied force to move the rotor. Further, if you can then change the polarity of the applied voltage to the coil as it moves and tends toward an alignment of the magnetic fields, you can get the rotor to rotate continuously. The torque delivered by the interaction of the generated and the fixed magnetic fields will not be linear, but will be sufficient to spin the rotor. The rotor will turn toward a point where the magnetic fields can be "aligned" with Norths to Souths. At a point "half way" through the rotation where the fields are coming into alignment, a set of contacts or brushes on an armature reverse the polarity of the applied voltage to the coil. This sets up a reverse current in the coil, and a reverse magnetic field around the coil. This again "bucks" the stationary field of the stator's permanent magnets. The rotor again responds to the torque generated by the interacting magnetic fields, and it rotates more. And again the commutator breaks the circuit to the coil in the rotor and reverses the polarity of the applied voltage. This process repeats, and the rotor is in continuous motion. Though there are variations on the theme, the simple idea delineated here is what makes the basic DC motor function. Use the links below to learn more.
