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Why relay contact haS two different ratings for AC VOLTAGE and DC VOLTAGE?
Wiki User
∙ 13y ago
AC IS +/- WHILE DC IS JUST A LEVEL AC120 MUST WITHSTAND THE PEAK VOLTAGE
Reply: How is putting the two sets contacts in series going to help?The same potential is still being broken at the first set of contacts.>-------------0___0--------0___0---------->Parallel would make more sense to me, since then the current would be split between the two sets of contacts.
Wiki User
∙ 13y ago
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What happens when a relay is operated beyond its rated voltage or current?
Generally speaking, a relay is an electrically operated switch. As such, there are two sets of ratings associated with a relay. The operating voltage will be specified, and the ratings of the contacts are also set down. As regards exceeding the operating voltage, this will cause excessive current to flow in the relay when it is energized. If the voltage is not significantly higher than the rating, and if the relay is not operated often or for long, it will function normally, but probably with a shorter life. At some point, excessive operating voltage will cause the coil in the relay to fail. Operating a relay to energize an electrical circuit with a higher voltage or current than the relay is designed for will shorten the life of the contacts in the relay. Higher voltage and current will quickly burn the contacts and destroy them. This is particularly true if that voltage or current is significantly higher than the ratings set by those who designed and constructed the relay. Things might work for a short time, but not for long.
What is the current rating for a 48 VDC contact relay?
The current ratings of the contacts of a relay are written on the side of the protective envelope that covers the contacts.
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.
How do you control 110 volt circulator pump with a 24 volt thermostat?
You will need an interpose relay. This relay will have a 24 volt coil. The circuit power for the relay will come from a 120VAC to 24VAC volt transformer. The 24 VAC circuit will have the thermostat in series with the coil of the relay. Thermostat calls for heat, the coil energizes and the relay's contacts close. Your circulator pump is controlled by the relay. On selecting the relay make sure that the contact ratings can handle the full load amps of the circulator. A contact rating of 120 volts at 15 amps will do very nicely.
Can you use a 50 amp automotive relay with a 12V dc coil to control 12V ac 500 watt halogen lighting?
No, you cannot use a 50 amp automotive relay with a 12V DC coil to control 12V AC 500 watt halogen lighting. Automotive relays are designed to work with DC power, not AC power. Additionally, the amp rating of the relay refers to its capacity for DC load, not AC load. You should use a relay specifically designed for AC applications with the appropriate voltage and current ratings.
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.
What happens when a relay is operated beyond its rated voltage or current?
Generally speaking, a relay is an electrically operated switch. As such, there are two sets of ratings associated with a relay. The operating voltage will be specified, and the ratings of the contacts are also set down. As regards exceeding the operating voltage, this will cause excessive current to flow in the relay when it is energized. If the voltage is not significantly higher than the rating, and if the relay is not operated often or for long, it will function normally, but probably with a shorter life. At some point, excessive operating voltage will cause the coil in the relay to fail. Operating a relay to energize an electrical circuit with a higher voltage or current than the relay is designed for will shorten the life of the contacts in the relay. Higher voltage and current will quickly burn the contacts and destroy them. This is particularly true if that voltage or current is significantly higher than the ratings set by those who designed and constructed the relay. Things might work for a short time, but not for long.
How do you Calculate the contact rating of relay for AC and DC?
On the side of the relay there is a name plate that tells you the current carrying capacity of the contacts. It gives you the ratings at different AC voltages and a DC rating of the contacts at different voltages.
What is the current rating for a 48 VDC contact relay?
The current ratings of the contacts of a relay are written on the side of the protective envelope that covers the contacts.
How a dry contact can break 220V circuit?
The fact that it is a dry contact has nothing to do with the amount of voltage it will handle. Contact voltage capacities are rated by the air space between live parts. The further the space, the higher the voltage will be allowed. What limits the contacts are the amount of current they can conduct. Usually relay contacts have the contact rating printed on the side of the relay enclosure. The terminology of a dry contact is, a contact in another piece of equipment that is used to close a relay in a "hot" complete circuit. e.g. An automatic transfer switch has a dry contact that when it closes on a power failure it closes the circuit for the engine start circuit to start the generator.
Wire to electric fuel pump has low voltage?
if you have checked the voltage with a dvom then you need to verify that the power source at the fuel pump relay is correct, if it has the correct voltage pre-relay then your problem is post-relay. if the voltage is not correct pre-relay then simply trace and repair the power source. if the problem is post relay then check the output voltage directly at the relay, if voltage is good trace and repair line from relay to pump. if voltage is not correct then replace the fuel pump relay
Drop out voltage of a solid state relay?
Typically, when the coil voltage on a relay is decreased gradually, the relay "hold" will release at a certain voltage. This is usually defined as the Drop-out voltage (defined at some minimum value). Now, in the case of latching relay, the Drop-out voltage is called the Reset voltage.
What is the voltage from ecu to fuel pump relay 94 Hyundai scoupe?
The exact measurement of voltage from ECU to fuel pump relay 94 Hyundai Scoupe is unknown. Test it on your neighbour first. If he passes out upon contact, then it is good to go.
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.
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 Under voltage relay?
Under voltage relay provides a signal (Contacts) when the supplied voltage drops below a preset value.
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.
