The Siemens 3RH1921-1EA02 is a 2-pole auxiliary switch block from the SIRIUS 3RH19 series, featuring 1 Normally Open (NO) + 1 Normally Closed (NC) contact configuration. Designed for snap-on mounting on Siemens SIRIUS 3RT1 (S00, S0, S2) contactors, it provides auxiliary contact expansion for control circuit applications. The NO contact (11-12) typically signals contactor energized status to a PLC, while the NC contact (21-22) is commonly used for safety chains or fault indication. Rated for 10A at 24V DC, 6A at 230V AC (AC-15), and 2A at 110V DC (DC-13), with 500V rated insulation voltage and 6kV impulse withstand. Screw terminal connection, IP20 protection, operating temperature -25°C to +60°C, compliant with IEC 60947-5-1.
FAQ
Q: What is the contact configuration of the 3RH1921-1EA02?
A: 1 Normally Open (NO) + 1 Normally Closed (NC) — circuit diagram 11-12 for NO and 21-22 for NC.
Q: Which Siemens contactors is this compatible with?
A: SIRIUS 3RT1 contactors in sizes S00, S0, and S2 (may require specific arrangement for S2).
Q: How does the NO and NC contact differ in application?
A: The NO contact (11-12) closes when the contactor coil is energized, typically used for run status signaling. The NC contact (21-22) opens when energized, commonly used for safety chains or fault/off indication.
Q: What are the DC switching ratings?
A: 10A at 24V DC, 2A at 110V DC, and 1A at 220V DC under DC-13 utilization category for inductive DC loads.
Q: Does this block use screw or spring terminals?
A: Screw terminals. For spring-loaded (cage clamp) terminals, use the 3RH1921-1HA02 or 3RH1921-1DA02 variants.
Q: How many switching cycles can this block handle?
A: Over 10 million mechanical cycles and over 1 million electrical cycles under AC-15 load conditions.
Q: What is the insulation voltage?
A: Rated insulation voltage of 500V AC with 6kV impulse withstand capability.
Q: Is this suitable for safety applications?
A: The NC contact (21-22) is commonly used in safety chains for feedback signals, but always verify against the specific safety system requirements and applicable standards.
