Short Circuit Protection

Written by Kevin Tavolaro
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In order to secure the dependability of a system that deals with high voltages, short circuit protection must be implemented. The generation of high voltages produces heat, which can rapidly build up and spread through a system if not properly regulated. Excessive heat can easily damage sensitive components, such as circuit boards, which can lead to problems ranging from a temporary system shutdown, to serious irreversible damage to the application.

An often overlooked type of short circuit protection involves visually examining the system prior to operation. This entails first checking for stray pieces of wire, solder, or screws, which can cause malfunctions just by coming into contact with sensitive circuits. The second step in this process is to examine transformers for any leakage, which is the first sign of an impending short. Finally, the system should be reviewed for any loose, eroded, or broken connections, which must be remedied before operation can resume.

Types of Short Circuit Protection

One of the prime difficulties encountered in a system is that the transistor is in series with the electrical load. Because of this, a short that develops in the load will be transmitted directly to the regulator circuit, which will damage the pass transistor, and can potentially disable the entire device, causing serious damage to the application. One way to protect against this is to install a fuse in the circuit. The fuse intercepts the short as it passes through the circuit, and automatically blows. This action prompts the device to momentarily cease functioning, which halts the current flow before the short reaches the regulator. While this approach can be effective for preventing damage, it still entails the sudden shut down of the device, which can have drawbacks, especially when working with computers, which may lose data as a result.

Another method of short circuit protection is the use of a current-limiting circuit. As the name implies, a current limiting circuit limits electrical current to a safe value automatically. This component is installed in the system, and much like a transformer, automatically detects voltages and adjusts them according to what is safe for the area. This is done via a dual-winding system, in which two coils intercept and reprocess the energy. The first coil is charged, and absorbs the electrical current as it passes. It then redirects the current to the second, uncharged, coil. The current is adjusted during this interaction, according to preset specifications. The second coil then transmits the energy, now at a level that poses no danger for the area it is crossing.

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