Signal Isolators

Signal isolators are used to connect a grounded signal source to a grounded signal follower. If the speed control input of an adjustable frequency drive is grounded, any input signal must be ungrounded. A signal isolator provides electrical (galvanic) isolation between the input and output circuits. It converts the input into a frequency and then couples the signal to the output through a transformer or optical isolator. Signal isolators also break the direct electrical (galvanic) path between two or more loop points. They are used to protect against dangerous measured-variable voltages and provide increased protection from surges and spikes.

Selecting signal isolators requires an analysis of product specifications. There are three basic types of products: four-wire isolators, loop-powered isolators, and two-wire isolator transmitters. Each type of device should provide signal isolation between the input, output and power source. A typical signal isolator is capable of withstanding 1000 V, or more common-mode signals at the input. Signal ground isolators are used to remove the DC circuit path from the audio shield ground circuit. Generally, ground signals are present wherever multiple grounding is involved. As a rule, a signal source produces sine waves. Signal sources can be categorized as continuous wave (CW), which generates a single frequency, fixed sine wave; swept, which sweeps over a range of frequencies and may be phase-continuous; or signal generator, which adds modulation and produces a “real world” signal. An input signal is a control signal or sensor and can be isolated, filtered, amplified, scaled and/or liberalized by a micro-processor. Input signals are converted to a binary, weighted, digital word and transmitted serially (one bit at a time).

Signal isolators are used in industrial, medical and other environments in which electrical isolation is essential for safety. Signal isolators are also used to amplify signals, enabling instruments to be added to an overburdened loop, or stepping down dangerous, high-voltage signals to safer levels. Signal isolators are useful in breaking ground loops (circuits where extraneous currents flow in the signal path and add to the signal) and providing high-voltage common mode rejection (HVCMR).

• ANI-001: Intermodulation Distortion (IMD) Testing of Ferrite Circulators and Isolators
  Intermodulation Distortion (IMD) measurements are used to characterize the non-linearity of RF components, including ferrite circulators and isolators. Two CW tones (f1 and f2) are combined and fed...
  (read more)
• Fill 'Em Up
  This quick, one-time registration gives you access to members-only site benefits. A larger contract filler, Thorpe explains, will consider taking on a small job for an established customer with whom...
  (read more)
• Design and Development of Medical Electronic Instrumentation
  PREFACE The medical devices industry is booming. Growth in the industry has not stopped despite globally fluctuating economies. The main reason for this success is probably the self-sustaining...
  (read more)

Pages: 1 - 3 of 729

Part Numbers for Signal Isolators