Square D 1861-S1-R37A Contactor Coil Assembly

Square D 1861-S1-R37A Contactor Coil Assembly is a replacement magnet coil for Square D 1861-S1 Type S contactors, manufactured by Schneider Electric under the Square D brand. The coil is rated for 550/600 VAC and operates at 50/60 Hz, providing the energizing signal that pulls in the magnetic core to close the contactor's main power contacts in motor-control and industrial automation circuits. This coil assembly is designed to fit 1861-S1 contactors and is identified by the R37A suffix as the 600-volt variant within the 1861-S1 family. Verified distributor listings confirm the 600 V (550/600 VAC) rating and 50/60 Hz operation for this model. As a replacement component, it is used to restore coil energization for control circuits that formerly relied on the 1861-S1 coil, helping to maintain reliable switching of loads such as motors, pumps, fans, and other equipment controlled by Square D Type S starters. Note that this specific coil variant is listed as discontinued by the manufacturer, so compatibility with remaining 1861-S1 assemblies should be confirmed before replacement.