Siemens 3RV1901-1A Side-Mounted Auxiliary Contact

Full Product Name: SIRIUS Classic side-mounted auxiliary contact (lateral auxiliary switch)

Suitable for legacy 3RV1 motor protection circuit breakers, frame sizes S00 / S0 / S2 / S3; screw terminal, 1NO+1NC (1 normally open + 1 normally closed)

Lifecycle: Obsolete (Phase-out). It is an accessory for the older 3RV1 platform; the manufacturer promotes the upgraded 3RV2 platform.

Key Specifications

Contact configuration: 1NO + 1NC

Mounting: Lateral side mounting (distinguished from front-mounted 3RV1901-1E)

Wiring: Screw-clamp terminals

Contact rating: AC-12, max. 6A / 240V AC; commonly used for 24VAC/DC, 220VAC signal feedback in control circuits

Protection: IP20

Application: Passive feedback of circuit breaker ON/OFF status for PLC, indicator lamps and circuit interlocks

Compatible breaker bodies: 3RV10, 3RV11, 3RV13, 3RV14, 3RV16 and other legacy 3RV1 motor protectors; not directly compatible with the new 3RV2 series

Model Code Explanation

3RV1: Legacy SIRIUS motor protection circuit breaker series

3RV19: Accessory group for the 3RV1 series

01: Auxiliary switch

1A: Lateral mounting, 1NO+1NC, screw terminals

Replacement Options (Important)

1. If migrating to 3RV2 circuit breakers: Front auxiliary contact 3RV2901-1E (1NO+1NC, screw); lateral type 3RV2901-2E (2NO+2NC)
2. If keeping the existing 3RV1 breaker body: Only stock / second-hand 3RV1901-1A is available; 3RV29xx accessories cannot be fitted onto legacy 3RV1 breakers
3. Other accessories of the same series for reference:

3RV1901-1E: Front-mounted auxiliary contact, 1NO+1NC

3RV1901-1J: Lateral, 2NO

3RV1901-1C: Lateral, 2NC

Full Accessory List for Siemens 3RV1 (Legacy SIRIUS Motor Protection CB)

Compatible bodies: 3RV10 / 3RV11 / 3RV13 / 3RV14 / 3RV16; frame S00, S0, S2, S3; entire series obsolete. Accessories fit only 3RV1 bodies and cannot be installed on 3RV2

Terminal distinction: -1xxx = screw terminals; -2xxx = spring-cage terminals

1. Auxiliary Contacts (Status feedback, reflects CB ON/OFF position)

Limitation: Maximum one lateral auxiliary contact per 3RV1 breaker; front-mounted + lateral can be used together.

2. Fault Signal Switch (Trip signal, distinguishes overload / short-circuit, not equal to standard auxiliary contact)

3. Undervoltage Release (UVT, trip on loss of supply)

4. Shunt Release (SHT, remote tripping)

Release rule: Undervoltage release and shunt release are mutually exclusive, cannot be fitted on the same breaker.

5. Door-coupled Rotary Operating Mechanism (External cabinet operation, IP65, padlockable)

Function: Cabinet door cannot be opened when CB is closed; lockable in OFF position to prevent accidental closing.

6. Busbar Modules (Main circuit interconnection for side-by-side mounting)

S00 / S0 Frame

S2 Frame

7. Contactor Link Module (Direct assembly for 3RV1+3RT1 starter group, no extra busbar)

8. Seals, Covers & Other Mechanical Accessories

Cross Reference for Migration to 3RV2 Platform

Key Selection Notes

1. Standard auxiliary contacts (3RV1901): Only indicate handle position, cannot distinguish fault trip. Fault alarm requires 3RV1921-1M.
2. Undervoltage release: The breaker must be closed before supply is restored; it trips automatically when supply fails. Shunt release: Trips when energised.
3. Busbars have two versions: standard and accessory-space type. If auxiliary contacts are fitted on the side, select suffix 3AB/3BB/3CB.
4. Only stock items are available for purchase; manufacturer no longer accepts new production orders.

Operating Principle of 3RV1901-1A (Mechanically Synchronised Position Auxiliary Switch)

Core summary: Pure mechanical linkage, contact state follows the mechanical position of the 3RV1 handle synchronously. It only reflects ON / OFF status and cannot detect overload or short-circuit faults.

It is a passive snap-on auxiliary contact module clipped to the side of the 3RV1 motor protection circuit breaker. No electromagnetic components or trip detection mechanism inside.

1. Mechanical Linkage Structure

The operating mechanism of the breaker handle and main contacts has a drive cam. Once 3RV1901-1A is fully engaged, its internal lever bears against this cam:

Handle movement → cam displacement → actuates internal rocker mechanism of auxiliary contact

Internal double-break silver bridge contact, one changeover contact (CO:1NO+1NC) with snap-action spring to ensure clean switching without chatter.

Operating States

1. Circuit Breaker ON

Handle switched to ON position, cam fully advanced: NO closed, NC open

→ ON signal to PLC, run indicator lamp energised

2. Circuit Breaker OFF (Manual opening)

Handle switched to OFF position, cam retracts: NO open, NC closed

→ Stop status feedback

3. Circuit Breaker Tripped by Overload / Short-Circuit

⚠️ Important: After tripping, the handle rests in the intermediate trip position. The handle mechanism also drives the cam, so 3RV1901-1A switches to OFF state (NO open, NC closed).

✅ Limitation: This contact alone cannot tell whether opening is manual or fault-induced.

👉 Separate fault alarm requires 3RV1921-1M (fault signal switch). It has an independent trip plunger and only switches state on overload/short-circuit trip; no action on manual ON/OFF.

2. Electrical Characteristics

Passive dry contact, no internal power supply; it is simply a mechanical switch to route low-current signals for PLC digital inputs, lamps and interlock circuits.

Utilisation category AC-12: 6A / 240V AC. Designed exclusively for control signal circuits, not permitted for main power circuits.

Contact timing: Switches nearly synchronously with the main breaker contacts, no advance or delayed action (slightly different from contactor auxiliary contacts).

3. Comparison with 3RV1921-1M (Common Pitfall in Selection)

4. Installation Constraints & Additional Notes

Lateral mounting. Maximum one lateral auxiliary contact (3RV1901-1A) per 3RV1 breaker; one front auxiliary contact (3RV1901-1E) may be added together.

Poor snap fit causes the internal lever to lose engagement with the cam: handle moves but auxiliary contact does not toggle (most frequent site fault).

Insulated housing separates high-voltage main circuit from signal contacts, meeting low-voltage isolation requirements.

Common Site Misconception

❌ Misunderstanding: 3RV1901-1A is a fault contact and triggers alarm when tripped

✅ Correction: It is only a position contact. An open signal from this contact to PLC merely means the breaker is not closed. Combine it with 3RV1921-1M using AND/OR logic to discriminate fault trip.