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How does a low voltage thermostat prevent arcing when breaking or making contacts?
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What is function of snubber circuit?
capable of resetting the transformer as well as eliminating leakage inductance voltage spike across the switch
What do line voltage thermostats have that low voltage thermostats don't?
Line voltage sometimes varies according to how much load there is from neighbours and other users. When the voltage is high, the water heats more quickly so that the thermostat cuts out sooner, so the amount of energy used ia about the same. <<>> It is the difference in construction of the two thermostats. A line thermostat uses a bi-metal sensor to open and close the line voltage. The room temperature fluctuation has to be greater between the stat turning on to off, as the differential setpoint can not be regulated as fine as a low voltage stat. A low voltage thermostat uses a mercury switch that is operated from a spring that senses the room temperature. Low voltage thermostats do not control the line voltage to the heater but use a remote contactor to open and close the voltage supply to the heater. There is a compensator in the low voltage stat that can be set for the contactor's coil current. This way the temperature generated by the coil of the remote contactor is nulled and the thermostat only reads the room temperature. The differential setpoint on a low voltage thermostat has a finer setting than that of a line thermostat, so a more accurate temperature is maintained.
Why stop button always have NC contact?
When the contacts are Normally Closed (NC) the stop button is "in series" with the supply voltage. By activating the STOP function the contacts open interrupting the flow of current.
Will multiple tripping of a circuit breaker damage the circuit breaker?
You don't specify whether you mean low-voltage circuit breakers, such as MCBs (miniature circuit breakers) or high-voltage circuit breakers. In either case, repeated tripping under fault conditions causes arcing which damages the main contacts of the circuit breakers. For this reason, high-voltage circuit breakers are taken out of service after a specified number of tripping operations, so that the contacts can be maintained or, if necessary, replaced. MCB contacts are inaccessible, and the MCB may eventually require replacing.
Vacuum bottle in vacuum circuit breaker?
Is a breaker whose contacts are in vacum cylinder. this done so the contacts will not be burnt and destroyed by the electrical arc draw while opening under load.Used in high voltage and high amp conditions.
If a baseboard heater has its own thermostat can you bypass it and wire it to a wall mounted thermostat?
Yes, but be sure you buy what is known as a `line voltage thermostat`when you do this since you have no control voltage but are simply breaking a line in the main power feed to turn the strip on and off.
How to Wire a low voltage thermostat for a 220v baseboard heater?
You will need a relay with a low-voltage coil and 220v contacts rated for the current load of the baseboard heater. If you have a low-voltage transformer, see what its output is rated at (typically 24 volts or less). Then go to an electronics parts store or call some place like Digikey (phone 800-344-4539) and tell them you need (for example) a double-pole single-throw normally-open relay with a 24 volt coil and contacts rated at 30 amps at 240 volts (change these numbers to match your situation). If you do not already have a low-voltage transformer the parts store call sell you one to match the relay coil voltage (be sure to specify if you are connecting the transformer input to 120 volts or 240 volts). Then wire it up as follows: connect the transformer output (24 volts in the example above) in series with the thermostat contacts and the relay coil. Connect the 240 volt supply to the moving arms on the relay, and connect the contacts the arms touch when the relay operates to your heater. Now when the temperature drops below its setting the thermostat contacts will close and connect the relay coil to the 24 volts, the relay will operate, and the 240 volts will be connected to the heater. When the temperature rises above the thermostat's setting, its contacts open, the relay contacts open, and the heater is disconnected. Depending on where you live there may also need to be circuit breakers, protective ground wires, etc.--ask an electrician.
What is restriking voltage?
Restriking voltage is transient voltage. During the arcing time, at current zero, the voltage that shows up across the contacts is the restriking voltage.
What supplies the voltage to the USB?
The two outside contacts (of four contacts) are connected to the power supply in the computer.
What is Under voltage relay?
Under voltage relay provides a signal (Contacts) when the supplied voltage drops below a preset value.
What is function of snubber circuit?
capable of resetting the transformer as well as eliminating leakage inductance voltage spike across the switch
Define recovery voltage in circuit breakers?
It is the transient voltage that appears across the contacts of the circuit breaker at or near the zero current instant during arcing period. A high frequency transient voltage appears across the contacts and is caused by the rapid distribution of energy between the magnetic & electric field associated with the station & transmission lines of the system at the zero current. This transient voltage is known as restriking voltage.
Why is low voltage used to control high voltage?
Switching High voltages requires more substantial apparatus. High voltage electricity can arc further and therefore distances between contacts need to be larger. This has cost and size implications. Youy dont want a massive throw switch in your tiny state of the art piece of equipment. Also the contacts in high voltage equipment are bigger as the voltage will erode smaller contacts quickly. This also raises cost.
How do you prevent arcing in electrical contacts?
Arcing is caused by current trying to sustain its flow by using the air as a conduit. If the travel is very far the arc will dissipate as lack of paths. If the current is great it may sustain itself. All contactor have a biult in shoot trough to channel the energy harmlessly, A capacitor across the contacts can help by absorbing the difference in voltage when the contacts disconnect or connects
What is HT breaker?
high voltage breaking capacity
What is wrong when you have to hold the contacts down in order to get the outside rheem heat pump to come on and stay running?
low voltage from thermostat is not properly connected to contactor. transformer is bad. contactor is bad. >>>>>>>>>>>> You have an open pressure safety switch on the outdoor unit or the control wiring from indoors to outdoors is too small a gauge which will lower your control voltage at the contactor.
What is rated voltage in open circuit test?
The maximum voltage that the electronic parts can conduct without breaking.
