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Electric motors typically have a surge (Also called in-rush or start up) current rating. When the motor is not energized it takes added power to start it rotating. This is just like when you step on the accelerator pedal to get your car moving and then ease off on the gas pedal when you get at speed. One rule of thumb is that the surge current may be as much as 6 times the running current.

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How do fuses work to prevent fires?

On a current surge that is larger than the rating amperage of the fuse, the link in the fuse melts and opens the circuit thereby stopping the current flow.


Is surge current the same as short circuit current?

Not usually, but it may depend on the context. For instance, surge current might be used for a generator that is going to start a motor. Motors draw high current as they start, then the current drops to a normal level, called RLA, or running load amps. Generators have a watt rating for continuous operation called running watts, but they also have a 'surge' rating. You might see a generator listed as a '6000/5200 watt. The 6000 watts is the 'surge' rating. This means the generator can supply 6000 watts for a few seconds, such as might be needed to start a motor, but cannot supply more than 5200 watts continuously. Short circuit current on the other hand simply means how many amps will flow instantaneously if you drop a wrench across the two wires! For a normal utility power service, the short circuit current, also called fault current, can be several tens of thousands of amps, even though the main breaker is only a couple hundred amps.


Why are surge protectors rated in joules?

Surge protectors are rated in joules because joules measure the energy a surge protector can absorb before it fails to protect your devices. The higher the joule rating, the more energy the surge protector can handle. Choosing a surge protector with a higher joule rating can provide better protection for your electronics.


What fuse rating do you need for an 11 amp circuit?

A fuse is designed to "open" if the current exceeds the specifications of what it is protecting. I have never heard of an 11 A circuit. If you are trying to protect a device that has an 11 A rating it needs an 11 A fuse. With a lesser rating the fuse will blow whenever the current exceeds the rating and if you use a higher rating it won't protect the device. Also recognize that fuses have different response times to allow some surge current without blowing. For example a skow blow fuse will allow an over-current for a small amount of time before blowing.


What is a surge in voltage or current in an electrical circuit called?

A transient, surge, spike, etc.


How many joules are in the newpoint surge protector 330V E87630?

The number of joules in a surge protector is a measure of its energy absorption capacity, not its voltage rating. In order to determine the joules rating of the Newpoint Surge Protector model E87630, you would need to refer to the product specifications or documentation provided by the manufacturer.


What features should I consider when choosing a long surge protector power strip for my home office?

When choosing a long surge protector power strip for your home office, consider features like the number of outlets, surge protection rating, joule rating, cord length, spacing between outlets, warranty, and compatibility with your devices.


What would be a typical joules rating for a surge suppressor designed for home use?

Destructive surges can be hundreds of thousands of joules. A protector rated for hundreds of joules does not claim to protect from the other and typically destructive surge. In fact, a 250 joule surge will simply be converted by electronics into low voltage DC to safely power its semiconductors. A destructive surge may be 20,000 amps. So a minimal 'whole house' protector for all homes should be at least 50,000 amps. Any protector that fails on a surge did not provide effective protection. And was a potential house fire.


What is the relation between surge current and fault current?

Fault/short circuit current is the available current from the source when a short circuit occurs. It is the maximum current the source can provide, defined as an RMS value, usually without any DC offset. Surge current is the maximum instantaneous current that is drawn by "turning on" or energizing a device such as a motor or transformer. Surge current will be less than fault current. If you assume a very strong source relative to the device rating, the surge current will be solely dependent upon the device in question (so fault current and surge current have no intrinsic connection). For a transformer, inrush may be 5-7 times the self cooled full load rating. Motors are usually less than this, and depending on the starting technique and configuration can be little (20-50%) over full load rating. From these definitions, and the above paragraph, it should be clear that if you have a weak source relative to the device, the device may not be able to draw as much current as it would if connected to a stronger system. If this occurs, the voltage will dip. An example would be a system where the available short circuit power is 600MVA; A 60MVA transformer is connected to this system bus. Energizing this transformer without any sort of controled closing could result in (7) x 60MVA = ~420MVA on inrush. This is relatively close to the available short circuit power (70%), so you can expect the system voltage to dip as a result. If the available short circuit current was around 20,000MVA, energizing such a transformer would not cause any significant system voltage dip.


What is difference between surge absorber and surge suppressor?

There is likely no difference. Neither is accepted terminology for a surge suppressive device (SPD). If these products have been tested by safety organizations such as CSA (Canada) or UL (US) or tested to international surge standards (IEEE, IEC), then they should bare the correct terminology, otherwise, they are not tested to provide protection to equipment during a surge. Surge Absorber acts as a load that utilizes the high current until it exhausts. but the surge suppressor diverts the high current into ground without reaching the sensitive parts of the circuit. Surge absorber degrades faster than a surge suppressor.


What is the current rating of an 18AWG wire?

The current rating of an 18AWG wire is typically around 16 amps.


What is the difference between an electrical surge and a brownout?

A surge is an over voltage and over current situation and a brownout is an under voltage situation.