Siemens 3RH2921-2DA20 Auxiliary Switch 2NO Lateral Spring Terminal

The Siemens 3RH2921-2DA20 is a SIRIUS laterally mountable auxiliary switch with 2 instantaneous normally open (NO) contacts. It snaps onto the left or right side of 3RT2 contactors and 3RH2 contactor relays, adding auxiliary switching paths via spring-loaded terminals rated to 690 V insulation voltage.

Technical specifications:

• MLFB: 3RH2921-2DA20
• Manufacturer: Siemens
• Product line: SIRIUS
• Product type designation: 3RH29
• Contact arrangement: 2 NO (instantaneous); 0 NC
• Terminal assignment - left: 53/54, 63/64; right: 33/34, 43/44
• Insulation voltage: 690 V AC (pollution degree 3)
• Surge voltage resistance: 6 kV
• Operational current AC-15 at 690 V: 1 A
• Operational current AC-12 at 24 V / 230 V: 10 A
• Operational current AC-15 at 24 V / 230 V: 6 A
• Operational current DC-12 at 24 V: 10 A
• Mechanical service life: 10,000,000 operating cycles
• Electrical endurance AC-15 at 230 V: 200,000 operating cycles
• IP rating (front): IP20
• Mounting: snap-on, laterally mountable
• Connection type: spring-loaded terminals
• Conductor cross-section: 0.5 to 2.5 mm² (solid, stranded, or finely stranded); AWG 20 to 14
• Dimensions (W x H x D): 10 x 64.8 x 66 mm
• Net weight: 46 g
• Operating temperature: -25 to +60°C
• Storage temperature: -55 to +80°C
• Compatible with: 3RT2.2, 3RT2.3, 3RT2.4, 3RH2

Features and benefits:

• Mirror contact function per IEC 60947-4-1 (when used with 3RT2 contactors)
• Lateral mounting on left or right side of contactor without additional tools
• Spring-loaded terminals allow tool-free wiring and accept two conductors per terminal
• High mechanical service life of 10,000,000 cycles for demanding duty cycles
• Contact reliability of 1 faulty switching per 100 million operations at 17 V / 1 mA
• Approved for railway and maritime applications

Applications:

• Auxiliary signalling and status feedback on 3RT2 motor starters
• Safety monitoring circuits requiring mirror contact verification
• Control interlocking with 3RH2 contactor relays
• AC and DC auxiliary control circuits up to 690 V
• Railway and maritime control panel wiring

Compliant with IEC 60947-4-1 (mirror contact) and IEC 60947-5-1. Part of the Siemens SIRIUS 3RH29 range.

Also known as: Siemens 3RH2921-2DA20, SIRIUS 3RH29 lateral auxiliary switch, 3RH29 2NO auxiliary switch spring terminal.