In addition to commonly used transformers, such as polyphase and resonant transformers, there is a whole field of other more specific types. Among them are isolation, zigzag, pulse, and speaker transformers.
Isolation Transformers
Although most transformers rely on the connection between windings which enables power to be transferred, isolation transformers are substantially different. In an insulation transformer, the primary and secondary windings are isolated from one another by insulation. This separation allows for an AC voltage to be transferred from one circuit to another while blocking DC signals and interference associated with ground loops. Generally speaking, isolation transformers are effective at power transfer in sensitive applications, such as computers and laboratory equipment. Hospital Grade isolation transformers can help protect sensitive equipment in medical environments.
Isolation transformers serve many unique functions that other transformers do not offer. For example, an isolation transformer can use the primary and secondary windings to increase or decrease the output, which makes it well suited to circuits with varying voltage loads. Additionally, isolation transformers can include Faraday shields, which lessen high frequency noise, improve power, and lower leakage currents.
Traditional transformers consist of primary and secondary windings around a core, and occasionally include a Faraday shield between windings to help reduce noise. Without a Faraday shield present, a fair amount of capacitance noise occurs between the windings.
Zigzag Transformers
Zigzag transformers have a primary winding but lack a secondary winding. Because they fall under the category of three-phase transformers, there are six coils on three separate cores. On each core, the first coil connects in a zigzag pattern to the second coil on the next core. Then, the second coils are joined and connected to the primary coils, comprising a neutral. Because the phases couple, the voltages cancel out, enabling the neutral pole to be secured to the ground. They resemble a Y transformer, whose neutral point is grounded. If one phases fluxes, all other phases are thrown out of balance; the zigzag formation, however, provides a path for earth faults (or zero sequence) to exit. Zigzag transformers are often applied to ungrounded electrical systems to derive a reference point.
Pulse Transformer
When it comes to transmitting a pulse with a fast rise and fall time, pulse transformers are optimal because they are specially designed for handling this type of electrical transfer. Because many different kinds of applications exhibit this type of pulse pattern (also known as rectangular electrical pulses), pulse transmitters can be made in a range of sizes to effectively handle a change in voltage magnitude. For smaller applications, pulse transformers called signal types are preferred, and are commonly used in applications such as telecommunications circuits. Medium-sized models are used for applications like camera flash controllers, whereas larger models play an important role in the power distribution industry. Read more about rectangular and other electrical pulses here.
Speaker Transformers
Speaker transformers are a type of electrical transformer that can power multiple loudspeakers with one circuit, as long as the circuit is performing at higher than normal voltage. They are referred to as constant volt or 70 volt speakers, despite the fact that the voltage is constantly changing. In terms of audio engineering, audio transformers can act as amplifiers by helping increase low-voltage output to the speaker circuit. At each speaker, an even smaller transformer alters the voltage and impedance, bringing them back up to standard speaker levels. The volume of each speaker can often be readjusted as needed. Using high-voltage and impedance speaker transformers minimizes power loss. All pulse transformers have a cycle of less than one; this means that at the end of the cycle any energy left in the coil must be disposed of before the pulse can run again.
