Finder Step and Impulse Relays

Step and impulse relays (impulse current switches, impulse relays) are modular relays that change contact position with each pulse received on the coil and keep that position after the coil power is cut. They are used to switch lighting on and off from multiple push buttons in areas such as corridors, stairwells and car parks, and to switch loads by pulse. The category includes Schneider Electric iTL and iTLI impulse current switches, ABB E290 impulse relays and Finder 20 series modular step relays; models with 16 A and 32 A rated current and 1, 2 and 4 poles are listed, along with coil voltages such as 230 V AC/110 V DC and 48 V AC/24 V DC. Select the rated current and number of poles according to the load to be switched, the contact arrangement (normally open or changeover) according to the circuit, and the coil voltage and type (AC or DC) according to the voltage of the push button circuit. In step relays with two contacts, the closing order of the contacts varies by type; verify it from the manufacturer's diagram. An impulse relay holds its position until the next pulse; it is not a substitute for a stairwell timer switch that turns the lighting off automatically after a set time.

Step and Impulse Relays Selection Guide: Technical Criteria & Application Standards