Siemens SIRIUS Monitoring Relays

Monitoring relays watch an electrical quantity and switch a contact when it leaves a set window. The SIRIUS range covers 3UG line and voltage monitoring — phase sequence, phase failure, under- and overvoltage — 3RR current monitoring relays that mount directly onto a 3RT contactor, and 3RQ coupling relays used to drive heavy loads from a PLC output.

SIRIUS Monitoring & Coupling Relays we supply

• Siemens 3RP2535-1AW30 — Timing relay, OFF delay with control signal 1 change-over contact, 15 time ranges 0.05 s..100
• Siemens 3RQ1000-1EB00 — Positively driven coupling relay in industrial enclosure 1 NO contact / 1 NC contact 24 V DC
• Siemens 3RQ1000-1EW00 — Positively driven coupling relay in industrial enclosure 1 NO contact / 1 NC contact 24 V to
• Siemens 3RQ1000-1GB00 — Positively driven coupling relay in industrial enclosure 2 NO contacts / 1 NC contact 24 V DC
• Siemens 3RQ1000-1GW00 — Positively driven coupling relay in industrial enclosure 2 NO contacts / 1 NC contact 24 V to
• Siemens 3RQ1000-1HB00 — Positively driven coupling relay in industrial enclosure 2 NO contacts / 2 NC contacts 24 V DC
• Siemens 3RQ1000-1HW00 — Positively driven coupling relay in industrial enclosure 2 NO contacts / 2 NC contacts 24 V to
• Siemens 3RQ1000-1LB00 — Positively driven coupling relay in industrial enclosure 4 NO contacts / 1 NC contact 24 V DC
• Siemens 3RQ1000-1LW00 — Positively driven coupling relay in industrial enclosure 4 NO contacts / 1 NC contact 24 V to
• Siemens 3RQ1000-2EW00 — Positively driven coupling relay in industrial enclosure 1 NO contact / 1 NC contact 24 V to
• Siemens 3RQ1000-2GW00 — Positively driven coupling relay in industrial enclosure 2 NO contacts / 1 NC contact 24 V to
• Siemens 3RQ1000-2HB00 — Positively driven coupling relay in industrial enclosure 2 NO contacts / 2 NC contacts 24 V DC
• Siemens 3RQ1000-2HW00 — Positively driven coupling relay in industrial enclosure 2 NO contacts / 2 NC contacts 24 V to
• Siemens 3RQ1000-2LB00 — Positively driven coupling relay in industrial enclosure 4 NO contacts / 1 NC contact 24 V DC
• Siemens 3RQ1000-2LW00 — Positively driven coupling relay in industrial enclosure 4 NO contacts / 1 NC contact 24 V to
• Siemens 3RQ1200-1EB00 — force-guided coupling relay in industrial enclosure 1 NO contact / 1 NC contact (24 V) 24 V DC
• Siemens 3RQ1200-1EW00 — force-guided coupling relay in industrial enclosure 1 NO contact / 1 NC contact 24 V to 240 V
• Siemens 3RQ1200-2EB00 — force-guided coupling relay in industrial enclosure 1 NO contact / 1 NC contact (24 V) 24 V DC
• Siemens 3RQ1200-2EW00 — force-guided coupling relay in industrial enclosure 1 NO contact / 1 NC contact 24 V to 240 V
• Siemens 3RQ4018-1AB00 — output coupler with integrated relay, 24 V AC/DC, 1 change-over contact, screw terminal, width
• Siemens 3RQ4018-1AB01 — output coupler with integrated relay, 24 V AC/DC, 1 change-over contact, screw terminal, width
• Siemens 3RQ4018-1AE00 — output coupler with integrated relay, 115 V AC/DC, 1 change-over contact, screw terminal
• Siemens 3RQ4018-1AF00 — output coupler with integrated relay, 230 V AC/DC, 1 change-over contact, screw terminal
• Siemens 3RQ4018-2AB00 — output coupler with integrated relay, 24 V AC/DC, 1 change-over contact, spring-loaded
• Siemens 3RQ4018-2AB01 — output coupler with integrated relay, 24 V AC/DC, 1 change-over contact, spring-loaded
• Siemens 3RQ4018-2AE00 — output coupler with integrated relay, 115 V AC/DC, 1 change-over contact, spring-loaded
• Siemens 3RQ4018-2AF00 — output coupler with integrated relay, 230 V AC/DC, 1 change-over contact, spring-loaded
• Siemens 3RQ4018-2AM08-0AA0 — output coupler with integrated relay, 24 V DC (0.7-1.25 x Us), 1 change-over contact
• Siemens 3RQ4018-2AN08-0AX0 — output coupler with integrated relay, 110 V DC (0.7-1.25 x Us) 1 change-over contact
• Siemens 3RQ4038-1AB00 — input coupler with integrated relay, 24 V AC/DC, 1 change-over contact, screw terminal, width
• Siemens 3RQ4038-1AB01 — input coupler with integrated relay, 24 V AC/DC, 1 change-over contact, screw terminal, width
• Siemens 3RQ4038-1AE01 — input coupler with integrated relay, 115 V AC/DC, 1 change-over contact, screw terminal, width
• Siemens 3RQ4038-1AF00 — input coupler with integrated relay, 230 V AC/DC, 1 change-over contact, screw terminal, width
• Siemens 3RQ4038-1AF01 — input coupler with integrated relay, 230 V AC/DC, 1 change-over contact, screw terminal, width
• Siemens 3RQ4038-2AB01 — input coupler with integrated relay, 24 V AC/DC, 1 change-over contact, spring-loaded terminal
• Siemens 3RQ4038-2AE00 — input coupler with integrated relay, 115 V AC/DC, 1 change-over contact, spring-loaded
• Siemens 3RQ4038-2AF00 — input coupler with integrated relay, 230 V AC/DC, 1 change-over contact, spring-loaded
• Siemens 3RQ4038-2AF01 — input coupler with integrated relay, 230 V AC/DC, 1 change-over contact, spring-loaded
• Siemens 3RQ4050-1SM50 — output optocoupler, 24 V DC, 1 NO contact, screw terminal, width 6.2 mm, thermal current 3 A
• Siemens 3RQ4050-2SM50 — output optocoupler, 24 V DC, 1 NO contact, spring-loaded terminal (push-in), width 6.2 mm
• Siemens 3RQ4052-1SM30 — output optocoupler, 24 V DC, 1 NO contact, screw terminal, width 6.2 mm, thermal current 6 A
• Siemens 3RQ4052-1SM40 — output optocoupler, 24 V DC, 1 NO contact, screw terminal, width 6.2 mm, thermal current 3 A
• Siemens 3RQ4052-1SM50 — output optocoupler, 24 V DC, 1 NO contact, screw terminal, width 6.2 mm, thermal current 2 A
• Siemens 3RQ4052-2SM30 — output optocoupler, 24 V DC, 1 NO contact, spring-loaded terminal (push-in), width 6.2 mm
• Siemens 3RQ4053-1SG30 — output optocoupler, 110-230 V AC/DC, 1 NO contact, screw terminal, width 6.2 mm, thermal
• Siemens 3RQ4053-2SG30 — output optocoupler, 110-230 V AC/DC, 1 NO contact, spring-loaded terminal (push-in), width 6.2
• Siemens 3RQ4070-1SB30 — input optocoupler, 24 V DC, 1 NO contact, screw terminal, width 6.2 mm, thermal current 6 A
• Siemens 3RQ4070-2SB30 — input optocoupler, 24 V DC, 1 NO contact, spring-loaded terminal (push-in), width 6.2 mm

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What to check before ordering

• Decide what you are actually monitoring: supply quality (3UG), motor load current (3RR), or interfacing a PLC output (3RQ).
• Confirm whether the setting is fixed or adjustable, and that your operating point sits mid-range.
• Check the output contact rating against the load — a coupling relay is often needed precisely because the PLC output cannot switch it.
• For current monitoring, check whether the relay is direct-mount or requires a separate CT.

Frequently asked questions

What does a 3RQ coupling relay do?

It converts a low-power PLC or controller output into a contact that can switch a real load — a contactor coil, a valve, a lamp circuit — while providing electrical separation between the control and load sides.

Which relay detects phase failure?

The 3UG line monitoring family.

Can a 3RR mount on my existing contactor?

3RR current monitoring relays are designed to mount directly onto matching SIRIUS 3RT contactors.

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