SWD – 15- or 20-A circuit breakers rated 347 V or less may be marked “SWD,” meaning that they are suitable for switching fluorescent lighting loads on a regular basis (NEC 240.83(D)).
Just so, what does the abbreviation SWD mean?
|SWD||Serial Wire Debug|
|SWD||Shift Work Disorder (circadian rhythm disorder)|
|SWD||Solid Waste Disposal|
|SWD||Short Wave Diathermy|
Can you use a circuit breaker as an on off switch?
Circuit breakers are not designed as replacements for relays, operating controls. When a circuit breaker is designed to also be routinely used as an on-off switch to control 277 volt florescent luminaires they are marked SWD, for switch duty.
Is a circuit breaker a switch?
A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit.
HACR type –This marking indicates the circuit breaker is suitable for use with the group motor installations typically found in heating, air conditioning and refrigeration equipment. TheNEC2005 no longer has this marking requirement.
SWD – 15- or 20-A circuit breakers rated 347 V or less may be marked “SWD,” meaning that they are suitable for switching fluorescent lighting loads on a regular basis (NEC 240.83(D)). These circuit breakers are evaluated for high endurance use, since they will be used similar to a light switch. 5.)
|HACR||Heating, Air Conditioning & Refrigeration|
|HACR||High Accuracy Cryogenic Radiometer|
|HACR||Honor All Cards Rule (credit cards)|
|HACR||Home Affairs Committee Report (House of Commons; UK)|
Fused disconnect switches and circuit breakers are both intended to open a circuit quickly in the event of a current overload or a short-circuit. A circuit breaker combines the functions of a switch and an overcurrent disconnect into one device.
A fuse is made up of a piece of metal that melts when overheated; a circuit breaker has an internal switch mechanism that is tripped by an unsafe surge of electricity. Fuses tend to be quicker to interrupt the flow of power, but must be replaced after they melt, while circuit breakers can usually simply be reset.
For protection against faults of this nature a circuit-breaker is used in place of a fuse. Circuit-breakers offer the following advantages compared to fuses. Unlike fuses which only operate once and need to be replaced a circuit-breaker can be reset.
They break the live wire if a fault causes the current to become too large. This is so that when a fuse blows it cuts off the live wire which is at a high voltage. The neutral wire is never at a high voltage. (Credit) You should be able to give a reason why a circuit breaker is better than a fuse.
Fuses and circuit breakers are designed to interrupt the power to a circuit when the current flow exceeds safe levels. As such, fuses and breakers are primarily intended to protect the wiring -- UL or CSA approval indicates that the equipment itself should not cause a fire.
A fuse is nothing more than a short length of wire designed to melt and separate in the event of excessive current. Fuses are always connected in series with the component(s) to be protected from overcurrent, so that when the fuse blows (opens) it will open the entire circuit and stop current through the component(s).
A fuse is a protective device that is designed to protect an electrical power system from the harmful effects of over-currents (currents higher than the normal operating current). Fuses are sacrificial in that they are generally good for one time use and are destroyed in the process of operating.
A fuse is exactly the same. It's a thin piece of wire designed to carry a limited electrical current. If you try to pass a higher current through the wire, it'll heat up so much that it burns or melts. When it melts, it breaks the circuit it's fitted to and stops the current flowing.
The fuse breaks the circuit if a fault in an appliance causes too much current flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.
The function of a fuse is usually to prevent fire - that's the basic protection a fuse offers - between power supply and appliance there may be a few feet or metres of cable - if a short circuit occurs in the appliance, the cable could easily become overheated (due to excess current) and burn or rupture its insulation.
A major circuit fuse is also known as a main breaker, and its function is to supply electricity to a building, normally at 240 volts to all circuits and outlets. But if the main breaker trips you have to switch off all the breakers on the electrical panel.
Relays are switches that open and close circuits electromechanically or electronically. Relays control one electrical circuit by opening and closing contacts in another circuit. As relay diagrams show, when a relay contact is normally open (NO), there is an open contact when the relay is not energized.
The control circuit functions as the coupling between the input and output circuits. In electromechanical relays, the coil accomplishes this function. A relays Output Circuit is the portion of the relay that switches on the load and performs the same function as the mechanical contacts of electromechanical relays.
A useful property of relays is that the circuit powering the coil is completely separate from the circuit switched on by the relay. For this reason relays are used where a safe low-voltage circuit controls a high-voltage circuit.
The heart of a relay is an electromagnet (a coil of wire that becomes a temporary magnet when electricity flows through it). You can think of a relay as a kind of electric lever: switch it on with a tiny current and it switches on ("leverages") another appliance using a much bigger current.
A relay is usually an electromechanical device that is actuated by an electrical current. The current flowing in one circuit causes the opening or closing of another circuit. Relays are used in a wide variety of applications throughout industry, such as in telephone exchanges, digital computers and automation systems.