A back-to-back connection is the direct connection of the output of one device to the input of a similar or related device.

Telecommunications

telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

s, a back-to-back connection can be formed by connecting a

transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...

directly to a receiver without a

transmission line In electrical engineering, a transmission line is a specialized cable or other structure designed to conduct electromagnetic waves in a contained manner. The term applies when the conductors are long enough that the wave nature of the transmi ...

in between.

Federal Standard 1037C Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms, is a United States Federal Standard issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, a ...

and from

MIL-STD-188 MIL-STD-188 is a series of U.S. military standards relating to telecommunications. Purpose Faced with "past technical deficiencies in telecommunications systems and equipment and software…that were traced to basic inadequacies in the applicat ...

This is used for equipment measurements and testing purposes. The back-to-back connection eliminates the effects of the

transmission medium A transmission medium is a system or substance that can mediate the propagation of signals for the purposes of telecommunication. Signals are typically imposed on a wave of some kind suitable for the chosen medium. For example, data can modulat ...

. In some cases, the output of a receiving device is instead connected to the input of a transmitting device.

Power transmission

A back-to-back connection for electric power transmission is a

high-voltage direct-current A high-voltage direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating curre ...

(HVDC) system with both ends in the same switchyard. This is used to couple asynchronously operated

power grid An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:Kaplan, S. M. (2009). Smart Grid. Electrical Power ...

s or for connecting power grids of different frequencies where no DC transmission line is necessary.

Electronics

electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...

, a back-to-back connection is the connection of two identical or similar components in

series Series may refer to: People with the name * Caroline Series (born 1951), English mathematician, daughter of George Series * George Series (1920–1995), English physicist Arts, entertainment, and media Music * Series, the ordered sets used in ...

with the opposite polarity. This is used to convert polarised components to non-polar use. Common examples include: * electrolytic capacitors *

zener diode A Zener diode is a special type of diode designed to reliably allow current to flow "backwards" (inverted polarity) when a certain set reverse voltage, known as the ''Zener voltage'', is reached. Zener diodes are manufactured with a great var ...

Notes

Telecommunications techniques High-voltage direct current Capacitors Diodes {{telecomm-stub