Relay FAQs:


Q: Is a relay an electrically operated switch?

A: Yes.

Q: Is a relay activated?

A: Yes, the circuit is connected when the relay is inactive.

Q: Are relays often used in transceivers which combine transmitter and receiver in one unit?

A: Yes.

Q: Is a relay a reed switch enclosed in a solenoid?

A: Yes.

Q: Are relays constructed with a kind of "shock absorber" mechanism attached to the armature which prevents immediate?

A: Yes, and full motion when the coil is either energized or de-energized.

Q: Is a relay a form of reed relay in which the contacts are wetted with mercury?

A: Yes.

Q: Are relays preferred?

A: Yes.

Q: Is a relay a relay that uses mercury as the switching element?

A: Yes.

Q: Is a relay de-energized there is an air gap in the magnetic circuit?

A: Yes.

Q: Are relays found in avionics and numerous industrial applications?

A: Yes.

Q: Are relays widely used on railways following British practice?

A: Yes.

Q: Are relays used wherever it is necessary to control a high power or high voltage circuit with a low power circuit?

A: Yes, and especially when galvanic isolation is desirable.

Q: Are relays made with different main contact sets?

A: Yes, and either NO, NC or changeover, and one or more auxiliary contact sets, often of reduced current or voltage rating, used for the monitoring system.

Q: Were relays the standard method of controlling industrial electronic systems?

A: Yes.

Q: Are relays equivalent to a pair of SPST switches or relays actuated by a single coil?

A: Yes.

Q: Are relays now rarely used?

A: Yes.

Q: Are relays used to switch low-voltage signals where the mercury reduces the contact resistance and associated voltage drop?

A: Yes, for low-current signals where surface contamination may make for a poor contact, or for high-speed applications where the mercury eliminates contact bounce.

Q: Is a relay matched to the transmission line impedance of the system?

A: Yes, for example, 50 ohms.

Q: Is a relay operating at its derated value?

A: Yes, and it is controlling a smaller value of current than its maximum make and break ratings.

Q: Are relays used to detect overload and other faults on electrical lines by opening and closing circuit breakers?

A: Yes.

Q: Are relays position-sensitive and must be mounted vertically to work properly?

A: Yes.

Q: Are relays switches, the terminology applied to switches is also applied to relays?

A: Yes, a relay switches one or more poles, each of whose contacts can be thrown by energizing the coil.

Q: Are relays in long telegraph lines?

A: Yes, where the weak signal received at an intermediate station could control a contact, regenerating the signal for further transmission.

Q: Is a relay being switched?

A: Yes, and the relay contacts retain this setting across a power outage.

Q: Were relays used for control of automated systems for machine tools and production lines?

A: Yes.

Q: Are relays large considering the mostly small voltages and currents that they switch?

A: Yes.

Q: Are relays devices which generally implement safety functions?

A: Yes.

Q: Are relays arranged for an intentional delay in operating their contacts?

A: Yes.

Q: Is a relay exposed to the same environment as the motor?

A: Yes, and a useful though crude compensation for motor ambient temperature is provided.

Q: Is a relay a specialized kind of multi-way latching relay designed for early automatic telephone exchanges?

A: Yes.

Q: Were relays replaced by delay line memory?

A: Yes, and which in turn was replaced by a series of ever-faster and ever-smaller memory technologies.

Q: Were relays used in middle 20th Century telephone exchanges to detect faint pulses and correct telegraphic distortion?

A: Yes.

Q: Are relays devices designed to work for wide voltage ranges such as 24 to 240 VAC/VDC and wide frequency ranges such as 0 to 300 Hz?

A: Yes.

Q: Is a relay a type standardized for industrial control of machine tools?

A: Yes, and transfer machines, and other sequential control.

Q: Are relays useful in applications where interrupted power should not be able to transition the contacts?

A: Yes.

Q: Is a relay used as a TR relay?

A: Yes, and which switches the antenna from the receiver to the transmitter.

Q: Is a relay driving a large?

A: Yes, or especially a reactive load, there may be a similar problem of surge currents around the relay output contacts.

Q: Are relays much more resistant than semiconductors to nuclear radiation?

A: Yes, and they are widely used in safety-critical logic, such as the control panels of radioactive waste-handling machinery.

Q: Is a relay a safety device sensing the accumulation of gas in large oil-filled transformers?

A: Yes, and which will alarm on slow accumulation of gas or shut down the transformer if gas is produced rapidly in the transformer oil.

Q: Were relays used extensively in telephone exchanges and early computers to perform logical operations?

A: Yes.

Q: Is a relay activated?

A: Yes, the circuit is disconnected when the relay is inactive.

Q: Were relays used in long distance telegraph circuits as amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on another circuit?

A: Yes.

Q: Is a relay a function of the material used to make the device?

A: Yes.

Q: Was a relay de-energized?

A: Yes, and then the movement opens the contacts and breaks the connection, and vice versa if the contacts were open.

Q: Is a relay derated?

A: Yes.

Q: Are relays used as part of an engineered safety system?

A: Yes.

Q: Are relays manufactured to operate quickly?

A: Yes.

Q: Are relays used where it is necessary to control a circuit by a separate low-power signal?

A: Yes, or where several circuits must be controlled by one signal.