Definition
An electromagnetic relay designed to operate on a very small amount of electrical current. Because it requires only a weak signal to close its contacts, it is typically used to detect low-current conditions and then switch a heavier load through its contacts.
Plain English
A switch that gets triggered by a tiny electrical signal. The small signal isn't strong enough to do real work, so the relay uses it to flip a much bigger circuit on or off.
Context Anchor
Seen in aircraft electrical system discussions, especially where a small signal from a sensor, switch, or control unit must operate another circuit.
Derivation
Sensitive' here means responsive to very small inputs -- the same sense as a sensitive instrument that reacts to slight changes. 'Relay' comes from old French 'relais,' meaning a fresh set of horses standing by to take over a journey -- the idea of one thing handing off work to another. Together: a switch that responds to a small signal and hands the job over to a stronger circuit.
Why Pilots Care
Allows reliable activation of critical alerts and controls from low-energy sources, preventing missed warnings that could affect flight safety.
Analogy
It is like a light-touch doorbell button: a small press does not power the whole chime by itself, but it starts the larger electrical action.
Intuition Check
Sensitive does not mean emotionally sensitive or fragile here. It means the relay operates with a very small electrical input.
Example Sentence 1
A sensitive relay was used to trigger the low-oil-pressure warning light when current through the pressure sensor dropped below a set value.
Example Sentence 2
During maintenance the technician applied a small test current to verify the sensitive relay would activate the overvoltage protection system.