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Too much current cause excessive heat and cuases melting of the relay contacts.
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∙ 10y ago
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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
Can a short circuit current through a photo cell damage it?
If the photo cell was on during the short circuit then the chances of damage to the photo cell are at a minimum. If the short circuit occurred when the photo cell was operated then yes damage to the internal contacts of the photo cell could have happened. What happens is, the short circuit is downstream from the photo cell and when the contacts of the relay close in the photo cell the dead short is applied to the contact faces of the relay. This is somewhat like striking an arc with a welded with the same results, the contact faces weld close and the circuits breaker trips to open the short circuit. With the pole faces of the photo cell's relay closed it gives the illusion that the photo cell is not operating. The photo cell's circuitry will be working but the relay will not drop the circuit open because of the welded contact in the relay.
What is a faying weld?
A "faying edge" is the edges of two materials that are to be joined. This is the surface of a member in contact with another member to be welded.
What is the difference between butt weld and socket weld?
A butt weld is a weld made between two straight cut profiles , a socket , or plug weld is made between a surface and a hole.
Which one is stronger field weld or shop weld?
When done correctly it doesn't matter where a weld is made.
On a contact or relay what can go wrong with the contacts?
they can either weld together or not make contact due to excessive currents
What is the application of normally closed relay contact?
There are numerous applications for a normally-closed relay contact. It is used whenever you want to disconnect a circuit when the relay coil is energised.
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 AC rating DC rating wrt Relay contact or contact of contactor?
The contact rating is normally given in AMPs or HP and refers to the load the "switch" in the relay can handle. The manufacture will specify the relay contact rating in the data sheet. This rating depends on the current being controlled by the relay, the connection type (how the relay is mounted) and the duty. A Normally open relay in pilot duty (clicked closed all day) may be only 10% of the same relay in intermitted contact duty. DC current requires a higher contact rating then AC. For example a relay rated at 1A @ 24vdc should also handle 1A @ 120vac and as the voltage increases the contact rating will lessen.
Is a bimetallic strip a relay?
No, but it controls one. When it makes contact the relay closes and the system comes on.
How does degauss work?
i think ,crt on which temporary magnetic field temporarily connected to the electrical earth by a relay contact (thats why the dwoning sound comes). Then the magnetic field generated is neutralised through the relay contact. in other words charge accumulated discharges to the earth through the relay contact.
Can a short circuit current through a photo cell damage it?
If the photo cell was on during the short circuit then the chances of damage to the photo cell are at a minimum. If the short circuit occurred when the photo cell was operated then yes damage to the internal contacts of the photo cell could have happened. What happens is, the short circuit is downstream from the photo cell and when the contacts of the relay close in the photo cell the dead short is applied to the contact faces of the relay. This is somewhat like striking an arc with a welded with the same results, the contact faces weld close and the circuits breaker trips to open the short circuit. With the pole faces of the photo cell's relay closed it gives the illusion that the photo cell is not operating. The photo cell's circuitry will be working but the relay will not drop the circuit open because of the welded contact in the relay.
What does nc and no mean in electrical terms?
nc: Normally Closed (contact is closed when power is not applied) no: Normally Open (contact is open when power is not applied) Applies to a relay ex...: when power is applied to a relay the no(Normally Open contact will close and allow current to flow between two terminals on relay).
What causes contact chatter in electrical circuit?
Overload can cause contact chatter. Once the contact closes, the voltage in the circuit collapses and that causes the relay to drop out. At this pint the relay energizes, since the voltage is back. This cycle will continue on.
Which relay terminal is the normally closed NC terminal?
The normally closed contact on a relay is the one that you can see physically touching each other. Remember that all readings are taken in the de energized state, e.g. no voltage applied to the relay's coil. When a relay is energized a Normally Closed (N.C.) contact will become open and vice versa a N.O. contact will become closed.
What is a faying weld?
A "faying edge" is the edges of two materials that are to be joined. This is the surface of a member in contact with another member to be welded.
What is the purpose of a seal-in contact?
This is a small electromagnet whose coil is in series with the relay contacts and whose contact is in parallel with them. The electromagnet is energized, closing its contacts in parallel with the relay contact as soon as the trip coil is energized, and drops out when the circuit breaker opens.
