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Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow; no direct conduction path is permitted. [ 1 ] [ 2 ] Energy or information can still be exchanged between the sections by other means, such as capacitive , inductive , radiative , optical , acoustic , or mechanical coupling.
Schematic diagram of an opto-isolator showing source of light (LED) on the left, dielectric barrier in the center, and sensor (phototransistor) on the right [note 1]. An opto-isolator (also called an optocoupler, photocoupler, or optical isolator) is an electronic component that transfers electrical signals between two isolated circuits by using light. [1]
A common design principle of these devices is a special galvanic isolation module between the input (control) and the output (switching) circuits of the relay. Interface relays are widely used in control and protection systems of high voltage (10-100 kV) electronic and electrophysical equipment and in high power installations.
Galvanic isolation is provided by the conversion of electric current to photonic flux through the space between the LED and the detector, regardless of the intervening medium. A third strategy is to use small capacitors to couple a modulated high-frequency carrier; the capacitors can stand off large DC or power frequency AC voltages but provide ...
The control signal must be coupled to the controlled circuit in a way which provides galvanic isolation between the two circuits. Many SSRs use optical coupling. The control voltage energizes an internal LED which illuminates and switches on a photo-sensitive diode (photo-voltaic); the diode current turns on a back-to-back thyristor ( TRIAC ...
The network isolator is a passive device, and functions without any requirement of an external power supply. A functional equivalent to network isolators is Ethernet over a small stretch of optical fibre, using media converters or Ethernet switches/network cards with fiber connections on each end.
Figure 1: The optical circuit symbol for an isolator Faraday effect. The main component of the optical isolator is the Faraday rotator. The magnetic field, , applied to the Faraday rotator causes a rotation in the polarization of the light due to the Faraday effect. The angle of rotation, , is given by,
In electrical engineering, an electrical isolation test is a direct current (DC) or alternating current (AC) resistance test that is performed on sub-systems of an electronic system to verify that a specified level of isolation resistance is met. Isolation testing may also be conducted between one or more electrical circuits of the same ...