BT137S-800F,118

Thyristors - TRIACs

The BT137S-800F,118 is a thyristor, specifically a TRIAC (TRIode for AC switch), and is commonly used as a higher power AC switch or electrical isolator. A TRIAC is a four-layer semiconductor device which is capable of blocking and passing current in both directions. It is similar to two thyristors which are connected in an inverse parallel formation, sharing the same gate terminal. In some circumstances, TRIACs have been referred to as silicon controlled rectifiers (SCRs).

Application Field

TRIACs are used extensively in industrial and domestic applications. These applications typically come in the form of controlling heating elements, light dimming and actuating relays. It has been previously used in phase-controlled powersupplies, phase-controlled motors, and light dimmers, and TRIACs are highly valued for their abilities to handle high wattages, high voltages and wide range of currents.

More specifically, the BT137S-800F,118 is particularly capable of providing great performance across many different applications. It is a zero-cross device which means it can switch off in both the forward and reverse direction when the gate triggers it. This makes it ideal for light dimming, motor speed controlling and EMI filters.

Working Principle

TRIACs are most commonly known for switching AC power and the BT137S-800F,118 is no different. When the TRIAC is turned ‘on’, it allows current to flow in both directions between the MT1 and MT2 terminals. This is achieved by creating a low resistance path between MT1 and MT2 which allows a current to flow across both junctions. The voltage and current then flow from MT1 to MT2, from MT2 to MT1, and from MT1 to MT2 respectively and continually. As a result, the device is considered to be bistable.

Moreover, TRIACs are also capable of controlling current flow. This is done by a process known as phase control,in which the period in which the device is biased to turn ‘on’ is varied. Depending on the delay — or the time it takes for a TRIAC to be triggered — varying levels of current can be achieved by the same TRIAC. This feature is beneficial in the operation of heating systems since it means that these can be adjusted to a desired level.

In conclusion, BT137S-800F,118 is an exemplary TRIAC which is highly valued for its ability to be used for light dimming, motor speed controlling and EMI filters. Through its bistable structure, this TRIAC is capable of supplying high wattages, high voltages, and a wide range of currents and by varying the period in which it is biased to turn ‘on’, it able to control current flow. With all its features taken into account, the BT137S-800F,118 is an important thyristor and its capabilities have made it a key component in the industrial and domestic sector.