Eventually, every plant electrical system will experience overcurrents. Moderate magnitudes of overcurrent can overheat system components and damage insulation, conductors and equipment — unless they are removed expediently.
Large overcurrents can destroy insulation and melt conductors, while very high currents can produce magnetic force capable of bending and twisting bus bars, pulling cables from terminals and cracking spacers and insulators. Damaging fault current and short circuits can produce fires, explosions, arc flash and arc blast, which could cause injury or death to plant personnel.
Plant managers must be proactive by designing electrical systems and providing programs and training that ensure the safety of their workers. Electrical power enters a typical manufacturing facility through medium voltage switchgear. From there, power is distributed to medium voltage equipment — typically motors — and to secondary substation transformers, which step medium voltage down to low voltage.
Low voltage switchgear further distributes the electrical power through feeders to branch circuits that consist of motor control centers and drives, load centers and associated support equipment such as metering modules, capacitors, harmonic filtering and uninterruptible power supplies. Some larger facilities also have paralleling switchgear used with onsite power generation or backup power generators, which operate through an automatic transfer switch.
In most cases, power from the load centers flows through distribution transformers, some of which step down the voltage further for lighting and control panels, and other panelboards that require voltages lower than Vac — typically V, V and Vac. No plant electrical distribution system would be complete without devices that protect circuits and equipment from overcurrent situations. Overcurrent is current that exceeds the ampere rating of conductors, equipment or devices under conditions of use.
Overcurrent includes both short circuits and overloads. During a short circuit, current flows outside its normal path. Insulation breakdown or faulty equipment connections can cause short circuits.
The load determines circuit current during normal fault-free conditions. However, during a short circuit, electrical current bypasses the load, taking the path of least resistance. System impedance — or ac resistance — determines short circuit or fault current magnitude, which can range from fractions of an Amp to kA or more.
An overload is an overcurrent condition within normal current paths — there is no insulation breakdown. However, if an overload is allowed to persist, it will cause equipment or wiring damage.
Temporary overloads can be harmless; sustained overloads can cause damage. Temporary overloads may be caused by momentarily pushing equipment past its limit, or from starting large motors or other inductive loads. Temporary overloads occur frequently, are typically harmless and should be allowed to subside.
Overcurrent protective devices should not open the circuit, allowing motors to start and loads to stabilize. Sustained overloads can be caused by continually overloading mechanical equipment, failed bearings or other equipment malfunctions. They are also caused by installing loads such as equipment or additional lighting circuits that increase power demand beyond planned capacity. If sustained overloads are not disconnected within appropriate time limits, they will eventually overheat circuit components and cause thermal damage to insulation and equipment.
The National Electric Code has established basic power system overcurrent protection requirements and recognizes fuses and circuit breakers as the two basic types of overcurrent protective devices.What kind of tile do you want in the bathroom? How many windows are you putting in?
Is there going to be a good amount of outlets in the home? The questions never stop coming. One you may be struggling with — or one you might not have put any thought to at all — is the choice of implementing circuit breakers or fuses in your electrical panel.
Each one has its strengths and weaknesses, and deciding between one or the other can be a tough call. How do you know which is safer? Roman Electric can help you make that choice, or at least help you weigh the pros and cons of both. Our electricians will work with you to develop the right solution for you, no questions asked.
Fuses, on the other hand, have a filament that physically melts, preventing the current from continuing to flow. However, the trouble for a homeowner lies in the replacement aspect of the process. When you add fuses, you have to put in ones that are outfitted for the ideal electrical load your home has.
A too-small fuse will overload early, while one that is too large will allow circuits to generate too much power before melting. They can also explode, sending dangerous pieces of shrapnel everywhere in the case of an emergency. On the other hand, circuit breakers tend to not be as dangerous. For those reasons, a circuit breaker is generally preferred over fuses. However, not every situation is the same. Close Menu. Looking for commercial services?
Learn More. Breakers On the other hand, circuit breakers tend to not be as dangerous.
Key Differences Between Fuses and Circuit Breakers
Sign up and save! Great offers and helpful tips straight to your inbox. Do Not Fill This Out. We're here to help. Read More.Fuse vs Circuit Breaker. Electricity is the main power source in our households and industry.
With its innumerous advantages, still electricity may cause problems in any application if not regulated properly. An overload in electrical power can damage any appliances or machinery connected to the power supply line; perhaps even cause loss of life. Both fuses and circuit breakers are devices used to prevent damage due to power overloads.
The idea behind the safety features like fuses and circuit breakers is to disconnect the internal circuit from the power main, when an excessive voltage or current tries to pass through that. Fuses are devices connected serially to a circuit in between the power supply and the internal circuit.
All electrical fuses share a common principle of operation, but there are numerous variations and adaptations to better suit the requirements of the electrical system. A fuse consists of a thin conducting wire with special thermal properties connected to two terminals at the ends. Every conductor shows at least a small resistance to the flow of current, and these current heats up the conductor. Fuses are designed such that, when the amount of current passing through the thin wire exceeds the allowable limit, the heat generated causes the melting of the metal wire, disconnecting the internal circuit from the power source.
Electrical characteristics of the fuses are rated, and the electrical system must operate within these rated values, to operate without any disruption. Fuses have a Rated Current INwhich is the maximum allowable current before the breakdown. Rated Voltage is the minimum voltage at which the circuit will become open due to melting of the wire.
Temperature affects the resistance of materials; hence the voltage at which the fuse blows. Therefore, temperature tolerance is also rated for a fuse and marked on the package of the fuse. The size of the fuse may vary from a centimeter to about half a meter. Also, the packaging also changes depending on the application.
Once a fuse is blown it has to be replaced with a new one. A circuit breaker is an automatic switch that is designed using electromechanical techniques to prevent power overload damage or short circuits. A circuit breaker has a solenoid inside, and it is kept at a certain voltage level, to keep the triggering mechanism in balance.
Once a fault is observed in the circuit, such as an overload or a short circuit, the switch is triggered, and the current flow is discontinued. After solving the pertaining problem in the electrical system, the circuit breaker can be switched back to on again. Like fuses, circuit breakers also come in many different sizes and packages, specialized to the requirements of the electrical system. They have current and a voltage rating indicating maximum allowable current and voltage.
Coming from Engineering cum Human Resource Development background, has over 10 years experience in content developmet and management. Leave a Reply Cancel reply.Fuses and Circuit Breakers both serve the same purpose — which is to protect electrical circuits by preventing overloads that can cause fires.
They both interrupt the flow of electricity, but in very different ways from each other. While a fuse is made of a piece of metal that melts when overheated, circuit breakers on the other hand, have internal switch mechanisms that can be tripped by an unsafe surge of electricity. Fuses can be quicker for interrupting the flow of power, but when they melt they must be replaced; circuit breakers on the other hand just need to be reset. Fuses come in different types — for both residential and commercial use.
The most common type is made from a metal wire or a filament that is enclosed in a glass or ceramic and metal casing. When electricity flows, the fuse will permit the power to pass unobstructed across the filament between circuits. If overloads occur, the filament melts and stops the flow of electricity. It will take some time for the filament to melt, and therefore any power surge is stopped. When a fuse is blown, it is to be discarded and replaced with a new fuse. There are different voltage and ratings that are available which handle different capacities of electricity.
The best fuse for a circuit is usually one that is rated for slightly higher than normal operating current. Circuit Breakers have two different ways of working — the first is through the use of an electromagnet and the other is through the use of a bi-metal strip. In both instances, when turned on, the breaker allows electrical current to pass from a bottom to an upper terminal across the strip.
Once the current reaches any unsafe levels, the magnetic force of the solenoid or strip becomes strong enough to throw a metal lever in the switch mechanism, breaking the current.Bussmann series - Selective coordination and transformers - Part 3 - Fuses and circuit breakers
The other option that can happen is that the metal strip can bend, throwing the switch and breaking the connection. In order to reset the flow of electricity, the switch can just be turned back on. This reconnects the circuit. Circuit breakers in many cases are found in a cabinet of individual switches known as the breaker box.
This simple switch action allows for an easy turn-off for individual circuits in a house when needed for working on a wiring in the location. Circuit breakers have other applications, such as using for ground fault circuit interrupter, or GFCI.
The function of this is to prevent electric shock, rather than just overheating. It breaks the circuit in an outlet if the current gets unbalanced. It can be reset by the touch of a button, and is generally useful in kitchens or bathrooms, where electrocution is a risk from the use of electrical appliances near water sources such as sinks or faucets.
Fuses are more inexpensive, available at nearly any hardware store. They react quickly to overloading, offering more protection to sensitive electronic devices.
The only problem in this is that if the circuit is prone to surges that regularly cause fuses to blow, then the quick reaction to the overloading can be a disadvantage. When fuses are blown, they need to be replaced. This can be difficult, especially in a dark room, or if the replacement fuse is not available at the time of need. In many instances, too, people find themselves replacing a fuse with the replacement fuses that actually has a higher voltage or current rating that is too high for the application or need — which can then cause an overheated circuit.
Fuses are generally speaking, easy to see which switch has been tripped, and which would need to be reset. The average homeowner would find it safe since there is no doubt about choosing the right fuse rating and all of the electrical connections are in the breaker box.
The disadvantage to using a circuit breaker is that it can be more expensive to install, repair and replace.
Fuses or Circuit Breakers: Which should you use?
This means it would be possible that electronics connected to the circuit could be damaged by energy that is just let through. It can be more sensitive to vibration and movement, which may allow for a switch to trip for reasons that are unrelated to electricity overloads.For most of us who work in the electrical design field, the question of circuit protection is omnipresent in our day-to-day efforts.
There are a myriad of circuit protection technologies available that address phenomenon such as high voltage transients, inductive kick-back, capacitive coupling, high inrush currents and ground faults, just to name a few. However, the most common circuit protection devices guard against over-current situations.
As most of us already know, over-current protection is typically achieved by incorporating either a fuse or a circuit breaker within the primary power feed. The biggest question that faces most electrical designers is which one of these devices to select for any given situation. More often than not, our selection of either fuses or circuit breakers is based on past experience and personal preference. In the context of any given industry, past experience is usually a good guide for this selection process.
However, when changing projects or moving to a new job, what may be comfortable to you, may not be appropriate for the new application. So what criteria do we use to select one or the other? The recurring argument that I have heard in favor of circuit breakers is that they are easier to reset after a failure situation has occurred. In these situations, the convenience of resetting the breaker only serves to postpone the inevitable correction or re-design of the circuit.
On the other side of the fence, the usual argument in favor of fuses is that they are dirt cheap. However, if a circuit blows fuses on a regular basis, the accumulated replacement costs associated with labor and down time can make a fuse set considerably more expensive over the long run.
Additionally, if a fuse set is specified as an integral part of a power disconnect, then the cost is comparable to the equivalent circuit breaker arrangement. It should come as no surprise that both fuses and circuit breakers have their pros and cons. Circuit breakers certainly have some very favorable attributes.
Another attractive attribute of breakers is that they are inherently safe. The electrical connections are typically located behind a protective panel, which completely eliminates any possibility of electrocution. This feature is quite valuable, especially in those situations when non-electrical personnel are required to service the equipment. A third feature is that they usually provide a visual indicator when they have tripped. For many professionals, fuse sets also have a number of desirable attributes.
As mentioned previously, they are particularly inexpensive when compared to their breaker counterparts. Wires are usually connected with integral screw-type terminal blocks. In addition to their mechanical simplicity, the electrical flexibility that fuses provide can be a considerable asset, especially when working with unique circuits.
In line fuse and/or circuit breaker? | O Gauge Railroading On Line Forum
In these cases, the selected fuse can be quickly changed for another unit that is better suited for the application. A good example of this is a machine that has a high power-up surge current. The original fuse specified may be quite adequate for the run current, but may blow each time the circuit is energized.
A fuse set allows the technician to quickly correct the situation at the minimal cost of a few new fuses. The original fuses are simply replaced with time delay, or slow-blow, units carrying the same current rating and the problem is instantaneously corrected. In that case, the breaker must be removed and replaced with an entirely new unit with a rating appropriate to the conditions.
The costs associated with a change like this are reflective of a new breaker and the labor to remove the old unit and replace it with the new one. A significant disadvantage of fuse sets is their exposed electrical connections. In the case of larger, snap-in fuses, the socket clips are exposed and in close proximity to the opposite side s of the circuit. When the enclosure housing the fuse set is opened, these sockets expose the technician to a live circuit.Is it necessary to have inline fuses between a newer transformer that has circuit breakers I have a MPC dual power transformer and the TIU?
Or are the built-in circuit breakers in the transformer more than enough protection? If in line fuses are recommended, are 10 amp automotive fuses a good choice?
Does the voltage rating matter or just the amp rating? I would use both plus a TVS.
Automotive fuses are fine. I'm sure others will chime in. TVS's are a must. It wouldn't hurt to add them farther down the line. On the forum the advice at one time last year was to add a TVS on each set of posts. So I did. Now it's "not necessary?? Leaving them there, or moving them elsewhere around the track, like near a finicky turnout, isnt going to hurt.
If I recall correctly, after X amount of surge, they are "used up". Actually, it's the MOV that gives up a little of it's life for each surge. Other than random semi-conductor failure, a TVS won't die unless it's overloaded by a really large transient that exceeds it's ratings. In answer to your other question, the voltage rating doesn't matter on a train layout.
The rating is the maximum voltage that the fuse or breaker can open safely. I would not use slo-blo fuses. Skip to main content. Thanks, Chris. Original Post. F feet Member. Kerrigan Member. A Adriatic Member. It has since been pointed out MTH added them in the tui.
Membership Required We're sorry.Few devices are more important to the safety of your home than the circuit breaker or fuse. Although each device goes about protecting your home in different ways, the basic idea is the same: to prevent overloaded circuits that could overheat and cause a fire.
Photo credit: Circuit Reference. Today, circuit breakers are the most common form of overload protection found in homes. Circuit breakers, usually found in breaker panels pictured above :. While circuit breakers are most commonly found in newer homes, many updated homes have breaker panels instead of fuse boxes.
Photo credit: High Electric Bill. Fuse panels like you see above are less common, but are still not uncommon to see, especially in older homes. We can see, then, that circuit breakers and fuses are similar in function, though different in design. So why have so many homes started using circuit breakers instead of fuses? In many ways, a circuit breaker is like a modern-day fuse; a properly installed breaker panel is often lower maintenance and easier to use for the average homeowner.
A house with amp service, for example, almost always needs to be upgraded, while a house with amp service and main fuse can be left on its own in certain instances. You can get in touch by phone at Circuit Breakers Photo credit: Circuit Reference Today, circuit breakers are the most common form of overload protection found in homes. Circuit breakers, usually found in breaker panels pictured above : Use either a bimetal strip or solenoid to trip a switch when current reaches unsafe levels Are easily reset if tripped Can contain GFCI-style breakers for extra protection in certain locations Protect your home from overloaded circuits and fire While circuit breakers are most commonly found in newer homes, many updated homes have breaker panels instead of fuse boxes.
Fuses Photo credit: High Electric Bill Fuse panels like you see above are less common, but are still not uncommon to see, especially in older homes. Fuses: Use a filament that melts when overloaded Must be thrown out and replaced completely when blown Cannot contain GFCIs like a circuit breaker Protect your home from overloaded circuits and fire We can see, then, that circuit breakers and fuses are similar in function, though different in design.
Which Is Better?