What it is and where it fits
The Siemens 3RH2140-1BF40-ZW97 is a size S00 auxiliary contactor with four normally open instantaneous contacts and a 110 V DC coil. It is designed to switch control signals and auxiliary loads in motor starter and contactor assemblies, and mounts via screw or snap-on onto a standard 35 mm DIN rail — typical for panel builders integrating into a motor control center or distribution board.
Contact ratings — what they mean for your circuit
The four N/O contacts carry rated currents that drop as DC voltage rises: 10 A at 24 V DC, 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, and 0.26 A at 600 V. At 230 V AC the contacts are rated 10 A, and at 400 V AC they carry 3 A. These are the maximum continuous currents at each voltage level — inductive loads, cable length, and ambient temperature will require derating. The contacts are rated for a switching frequency of 10 000 operations per hour at AC and 1 000 per hour at DC-12 duty.
Mounting and spacing
The 3RH2140-1BF40-ZW97 measures 45 mm wide, 58 mm high, and 73 mm deep. It mounts on a 35 mm DIN rail with screw or snap-on fastening. Clearance requirements: 10 mm upward, 10 mm forward, 10 mm downward, and 6 mm at the side. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward.