Commercial advantages of motor protection circuit breakers over fuses
For processing and manufacturing operations, protecting motors is crucial to maintaining productivity and managing maintenance costs. Because fuses cost less than circuit breakers, they have often been the choice for this application. But Schneider Electric circuit breakers have evolved in recent years and come into their own as users consider total cost of ownership. Comparing them with fuses reveals how they help machine builders and users to improve safety and reliability and lower costs. They also support energy management initiatives. Compared to motor fuses, motor protection circuit breakers have many advantages for both OEMs and end-users.
Total Cost of Ownership (TCO)
Total Cost of Ownership is often quoted by equipment suppliers when promoting their products, but what does it really mean? It is a financial term to help buyers and business owners determine the direct and indirect costs of a product or system. It conveys how the organisation uses its assets from cost of acquisition and operating costs, as well as costs related to replacement or upgrades at the end of the life cycle. A TCO analysis provides a cost basis for determining the total economic value of an investment. It moves the financial focus from the initial cost price to reflect its lifetime cost up to the point of disposal.
1. Consistent performance
One downside of fuses is that their performance can degrade due to aging, even causing them to open during normal conditions. Also, there is no way to test a fuse, so you will never know the exact current value that will cause it to open. In contrast, the testing of motor protection circuit breakers during manufacture and can retesting during their operating life maintains their performance.
2. Motor protection circuit breakers
The breaking capacity of motor circuit breaker circuit breakers can be greater than equivalent fuses (up to 150 kA). And under overload conditions, a circuit breaker can trip up to 1000 times faster than a fuse. Some circuit breakers also provide exceptional fault current limitation, a capability often associated only with fuses. This not only supports reliable protection; it also reduces asset aging and extends service life. Another aspect of protection to keep in mind is that it’s common for only one of three fuses to open, causing a motor to continue running on two phases, as well as experiencing an overload. This will never happen with a circuit breaker, which will always break all three phases simultaneously.
3. Enhanced safety and uptime
The connections to circuit breakers are behind the device, and operation can remote operation is possible. This makes breakers safer, especially for unskilled workers. One of the reported causes of fires in industrial environments is replacing a fuse with the wrong model or rating, or even with wires or paper clips. Using circuit breakers avoids these mistakes as they usually do not need replacement after a trip. Additionally, replacing fuses in control panels takes more time than reclosing a breaker. This means circuit breakers help cut downtime and production losses.
4. Cost savings
As mentioned above, the cost of a single fuse is a lot less than the cost of a circuit breaker. But, when considering complete installation, other costs come into play. First, that it requires three fuses for a three-phase circuit, with each fuse requiring the cost of a fuse base. Second, unlike circuit breakers, fuses do not have any built-in switching capability, so need an upstream switch. Fuses also need a larger enclosure, due to their heat dissipation. And finally, one of three fuses opening all three. be replaced. This requires an expensive replacement stock of fuses on hand. So, in total, the complete cost of using fuses can be greater than a circuit breaker. If replacement of circuit breakers is necessary, a single adjustable breaker covers several current ratings, reducing inventory.
5. Greater functionality
Unlike fuses, breakers offer extra functionality like earth leakage protection, and allow for system coordination between breakers (e.g. selectivity, cascading). Modern advanced circuit breakers offer many capabilities in a compact size with flexible designs that enable field-upgrading. Add-ons can include remote control and status indication, alarm and auxiliary contacts, power and energy measurements, and network communications.
Schneider Electric’s TeSys GV4 thermal-magnetic and magnetic motor protection circuit breakers, for example, feature advanced capabilities. For example, offering dual-motor class 10/20 for short circuit and overload protection for motors up to 115 A / 55 kW. Other options can include advanced protections like JAM and long start, pre-alarming and fault differentiation. For more information on TeSys breakers for machine protection Click here to learn more about solutions that can help protect your entire machine application, not only the motor.
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