Siemens 3RH5921-1FA22 SIRIUS Four-Pole 2 NO + 2 NC Auxiliary Contact Block

Overview

SIEMENS SIRIUS

3RH5921-1FA22 SIRIUS Four-Pole 2 NO + 2 NC Auxiliary Contact Block

A snap-mounted four-pole auxiliary block with two normally open and two normally closed instantaneous contacts and screw-terminal wiring.

At a Glance

Brand	Siemens
Model	3RH5921-1FA22
Product Type	Auxiliary contact block
Core Function	Extending contactor control circuits
Application	Auxiliary and power contactors

Two complementary contact pairs

Two NO and two NC contacts provide separate control-circuit paths.

Load-dependent switching

AC and DC utilization categories have different permissible operating currents.

Snap-mounted accessory

The block attaches mechanically to the corresponding contactor assembly.

Product Overview

3RH5921-1FA22 adds four instantaneous auxiliary contacts to the matching contactor arrangement.

The SIRIUS block uses screw terminals and supports control duties with voltage-dependent AC-15 and DC-13 current limits, together with a rated 690 V insulation level.

Ordering focus: Match the contactor attachment, 2 NO + 2 NC circuit arrangement and utilization-category current for each control load.

Key Functions

Extend the contact arrangement

Two normally open and two normally closed instantaneous paths provide additional control contacts.

Switch AC control loads

The AC-15 rating depends on operating voltage, from 6 A at 24 or 230 V to 1 A at 690 V.

Connect panel control conductors

Screw terminals accept the specified conductor sizes for auxiliary circuits.

Official Specifications

Contact configuration	2 NO + 2 NC, instantaneous; no changeover contacts
Mechanical attachment	Snap-on mounting
Electrical connection	Screw terminals
Rated insulation voltage	690 V AC at pollution degree 3
Rated impulse withstand voltage	6 kV
Front protection rating	IP20
Typical mechanical endurance	10,000,000 operating cycles
Typical electrical endurance at 230 V AC-15	200,000 operating cycles
AC-12 operating current	10 A at 24 V or 230 V
AC-14 operating current	6 A at 125 V or 250 V
AC-15 operating currents	6 A at 24/230 V; 3 A at 400 V; 1 A at 690 V
DC-12 operating currents	10 A at 24 V; 3 A at 110 V; 1 A at 220 V
DC-13 operating currents	6 A at 24 V; 2 A at 48/60 V; 1 A at 110 V; 0.9 A at 125 V; 0.3 A at 220/250 V
Operating ambient temperature	−25 to +60 °C
Storage ambient temperature	−55 to +80 °C
Auxiliary conductor cross-section	0.5–2.5 mm² for solid or stranded conductors and prepared fine-stranded conductors
Permitted AWG range	20–14
Mirror-contact function	IEC 60947-4-1
Dimensions (W × H × D)	44 × 38 × 51 mm
Accessory weight	72 g

Official source:Siemens exact auxiliary-block data sheet

Frequently Asked Questions

Can 3RH5921-1FA22 provide four normally open control contacts?

No, its fixed contact arrangement is two normally open and two normally closed contacts.

How do I attach 3RH5921-1FA22 to the corresponding contactor assembly?

The block uses a snap-on mechanical attachment.

Can 3RH5921-1FA22 switch a 5 A AC-15 load at 400 V?

No, the AC-15 operating-current rating at 400 V is 3 A.

Is a 6 A rating also valid for a 110 V DC-13 load on 3RH5921-1FA22?

No, the DC-13 operating-current rating at 110 V is 1 A.

Can I terminate a prepared 2.5 mm² flexible conductor on 3RH5921-1FA22?

Yes, prepared fine-stranded conductors are permitted up to 2.5 mm².

Does 3RH5921-1FA22 provide delayed auxiliary switching?

No, the two normally open and two normally closed contacts are instantaneous.

What storage temperature range applies to 3RH5921-1FA22 when kept as a spare?

The specified storage ambient range is −55 to +80 °C.

Compatibility & Ordering Notes

Before ordering 3RH5921-1FA22: Retain the matching snap-on contactor attachment and 2 NO + 2 NC arrangement, and size each auxiliary circuit from the relevant AC or DC utilization-category rating.

Compatibility Checklist for 3RH5921-1FA22

• Match the control schematic’s NO and NC positions.
• Use the voltage-specific switching current.
• Keep conductor sizes within 0.5–2.5 mm².
• Maintain the required enclosure protection around exposed wiring.

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