A relay is an electrical control device that, when given a specified input quantity and held for a sufficient time, causes a predetermined step change in the controlled quantity in an electrical output circuit. When the input quantity drops to a certain level and is held for a sufficient time, it returns to its initial state.
① Rated Operating Voltage: This refers to the voltage required by the relay coil for normal operation. Depending on the relay model, it can be AC or DC voltage.
② DC Resistance: This refers to the DC resistance of the relay coil, which can be measured with a multimeter.
③ Pull-in Current: This is the minimum current required for the relay to activate. During normal use, the applied current must be slightly greater than the pull-in current for stable operation. The applied operating voltage should generally not exceed 1.5 times the rated operating voltage; otherwise, excessive current will be generated, potentially burning out the coil.
④ Release Current: This is the maximum current required for the relay to release. When the current in the relay's pull-in state decreases to a certain level, the relay returns to its unenergized release state; the current at this point is much smaller than the pull-in current.
⑤ Contact switching voltage and current: This refers to the voltage and current that the relay is allowed to load. It determines the magnitude of the voltage and current that the relay can control. This value must not be exceeded during use, otherwise the relay contacts can easily be damaged.
