The Best Industrial Circuit Breaker Type for Your Application
by Simcona on Oct 10, 2023 7:03:02 PM
It’s relatively simple to pick an electronic component based on cost and supply availability. But that’s probably not what your operation needs when it comes to circuit breakers.
Industrial circuit breakers are a key player in protecting expensive electronic systems. That means you’ll have to seek a solution that’s convenient for not just today, but also 2 years from now (or more). There are many industrial and commercial circuit breaker types, and the wrong choice could cause production delays and safety hazards.
To simplify the buying process, check out these nine important criteria for choosing a breaker.
Types of Industrial Circuit Breakers
There are four main ways to classify breakers in industrial applications:
- Voltage – Can be low-, medium-, or high-voltage
- Location – Only certain breakers are rated for outdoor use
- Interrupting mechanism – There are many systems for stopping current flow and power, including MCCB, vacuum, air, oil, & ICCB
- External design – Can be dead tank (has an enclosure at ground potential, housing interrupting & insulating mediums) or live tank (housing interrupters are at potential above ground, with insulation in between)
It’s helpful to understand the lingo and acronyms of all the breaker types out there. But more importantly, you’ll need to know the green and red flags that’ll make or, err … break your project:
9 Steps Toward the Best Industrial Circuit Breaker Type
The top criteria for selecting an industrial-grade circuit breaker are:
- Voltage rating
- Current rating
- Interrupting capacity
- Tripping current level adjustment ranges
- Environmental resistance
- Number of poles
1. Voltage Rating
Matching your breaker to your application’s needs is probably your first order of business.
The rated voltage of a circuit breaker refers to the number of volts it can handle safely. A mismatch between the breaker’s rating and your system’s voltage levels can lead to inefficiency and may compromise safety.
Miniature (MCB) w/ trip ratings < 100 AT; molded case (MCCB) w/ ratings up to 2,500 A
Common industrial, commercial, & residential settings
Air, vacuum, & sulfur hexafluoride (SF6)
Power generation & distribution, industrial plants, commercial buildings, data centers
Typically 72.5+ kV
Solenoid-operated – includes vacuum, SF6, air blast, bulk oil, minimal oil
Power transmission networks & circuits
A circuit protector’s voltage rating depends on its insulation level, a trait that’s categorized into several levels. The level defines the thickness of the insulation within a single voltage rating. Common insulation levels include:
- 100% (grounded systems)
- 133% (ungrounded systems)
Always consult your assembly specifications and ensure that the circuit breaker can handle the voltage requirements.
2. Current Rating
Rated current is the maximum current that a circuit breaker can carry continuously in the ambient temperature where it was calibrated.
Continuous current rating should align with the requirements of your system.
A too-high current rating may keep the breaker from tripping when it’s supposed to. This allows excessive current to flow through the circuit, potentially leading to overheating, equipment damage, and even a visit from the fire department.
A too-low current rating will cause the device to trip too easily, even under normal operating conditions. This can result in frequent production stoppages, with the breaker becoming the very thing it was meant to prevent – downtime.
Tip: Miniature breakers and residual current circuit breakers (RCCBs) have particularly low current ratings and may not be suitable for heavy-duty protection.
The 80% vs. 100% Rulebook
You may be wondering when to use 80% (standard) vs. 100% rated breakers since they’re two commonly talked-about options.
First, remember that gradual heat buildup can hamper current-protection devices. NEC defines the concept of ”continuous” as a max current at 3 hours or more, and as such has recommended the 80% limitation to offset the effects of heat.
Generally speaking, there’s no need to protect 125% of a noncontinuous load requirement, and you can use a breaker size that meets 100% of the load. An 80% rated circuit breaker is usually the top choice in those situations.
3. Interrupting Capacity
You may know this concept as short-circuit rating, breaking capacity, or something similar.
The interrupting capacity is the highest amount of fault current that a circuit breaker can stop without sustaining damage. This is a critical safety feature, especially in industrial settings where high currents are common.
A breaker’s interrupting capacity must be equal to or greater than the potential fault current your system may produce where the breaker is applied.
The number of appliances and electronics requiring a higher interrupting capacity is on the rise. With many facilities running multiple large appliances simultaneously, it’s become easy to trip the old standby of 10,000 A capacity. Larger operations will value this spec more than others because it’ll allow them to function safely and avoid tripping the breaker repeatedly.
Tip: Molded case circuit breakers insulate all current-carrying parts and devices. They have higher interrupt ratings than miniature circuit breakers.
The frequency rating of a circuit breaker should match the frequency of your electrical system. (Sound like familiar advice?)
Mismatches can lead to operational inefficiencies and may even damage the circuit breaker or the system it protects. For example, using a circuit breaker rated for 50 Hz in a 60 Hz system could reduce the system’s power rating and shorten the breaker’s life span.
Circuit breakers up to 600 A can be applied to frequencies of 50-120 Hz. Assemblies with frequencies of more than 120 Hz frequencies will force you to derate the breaker.
5. Tripping Current Level Adjustment Ranges
Modern circuit breakers often come with adjustable tripping current levels for both overload and short-circuit protection. This feature allows you to better tailor the circuit breaker's performance to your needs.
- For overload protection – Industrial settings where you plan to connect machinery with different current requirements to the same circuit
- For short-circuit protection – Complex electrical systems where short-circuit current levels can vary wildly depending on the location of the system fault
Being able to adjust the tripping current can be particularly handy in systems with variable loads, empowering you to optimize protection while minimizing nuisance trips. It’s also more cost-efficient to tweak an existing setup rather than replacing it every time you make changes to your electrical system.
6. Environmental Resistance
If it exists in a factory or in the wild, there’s a chance it might pose a risk to your electronics.
Maybe that’s an exaggeration, but there’s no shortage of threats to consider when learning how to identify circuit breaker types acceptable in your application.
- High temperature – UL (Underwriters Laboratories) defines the acceptable operating temperatures for industrial circuit breakers to maintain performance both mechanically and electronically. The max temp is 122 °F in standard breakers and 140 °F in 100% rated breakers.
- Corrosion – Use a breaker with a special moisture treatment if your application will expose it to humidity or other moisture. Fungus isn’t the only corrosion threat; you should also keep breakers away from dangerous chemicals. If your application makes that impossible, be sure to specify a chemical-resistant breaker.
- Shock – Certain breakers include an anti-shock device that allows for use in hazardous areas. Shock-protection devices introduce a counterweight over the center pole; this holds the trip bar latched in normal shock conditions. Shock resistance is a key feature of marine-grade circuit breakers.
- Altitude – Above 6,000 ft., you must derate a breaker’s current, voltage, and interrupting capacity ratings. Thinner air isn’t as good at diverting heat from components, plus it slows dielectric charging when a breaker needs to withstand voltage. If you’re building a project for an environment like this, consider a circuit with higher ratings.
- Dust – Most, but not all, modern breakers are enclosed. This keeps harmful dust and dirt out of the device, promoting smooth performance.
Environmental threats are of special concern if you’re in an industry like oil and gas, food, or mining. If your project includes a unique or extreme environment, look for circuit breakers that have relevant certifications. Examples include IP ratings for dust and water protection, as well as compliance certificates for chemical and flame resistance.
An experienced electronics distributor and manufacturer can help you choose the component that’ll be safest in your application.
7. Number of Poles
What does the number of poles mean to a circuit breaker? It tells you how many separate circuits the breaker can protect at one time.
Breakers come in single-pole construction or multi-unit assemblies. Single-pole breakers are common in homes, but industrial applications often require multi-pole breakers for three-phase systems.
In the end, the choice between single and multi-pole will depend on the complexity of your electrical system. Consider also whether you’ll need to isolate individual phases for maintenance or troubleshooting.
Some models come with built-in testing features, while others may require external equipment.
Fortunately, someone’s usually done the up-front work: Most heavy-duty circuit breakers are UL Listed, meaning they’ve passed quality and reliability tests.
Note that manually operated breakers require less maintenance. They need only a simple cleaning of their contacts and verification that their linkages operate freely. Consider the ease and cost of maintaining the circuit breaker when making your choice.
Physical dimensions and setup matter beyond just the current rating of the circuit breaker.
Breaker size is an oft-forgotten consideration for settings where space is at a premium. Make sure your industrial breaker fits your panel or distribution board while still meeting other electrical requirements.
When it comes time to install the breaker, there are several more steps, including mounting, wiring, and testing. Consider the complexity of the setup process and whether you'll need specialized tools or expertise for a successful installation.
There are more circuit breaker mounting types than you could imagine. You can mount most breakers in any position, vertically or horizontally, without affecting their function.
In windy areas, the breaker should include an enclosure and be mountable on a surface that’s not overly rigid. A breaker attached to a stiff assembly may not perform as well in high winds.
The Best Circuit Breaker for Now … and 2 Years From Now
It’s not terribly tough to suss out 2024’s best circuit breaker brands when your only criteria are cost and supply availability. The true buyer knows how to look beyond the “right now” and find a match that’ll meet the application’s demands for both today and 2 years from now.
As always, make sure your desired breaker has the proper ratings to meet your system's levels. Too much or too little juice could put you back at square one, hunting for a new breaker again.
For more component-sourcing tips on quality, reliability, and on-time delivery, visit our resource hub. If you’re ready to hunt for breakers today, click below for a manufacturer list:
No Comments Yet
Let us know what you think