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Brand: Phoenix Contact
Phoenix Contact REL-MR-24DC/21 Plug-in Relay 24 V DC
Description
REL-MR-24DC/21: plug-in miniature relay, 24 V DC coil, 1 changeover contact
The Phoenix Contact REL-MR-24DC/21 (order no. 2961105) is a very slim plug-in relay, only 5 mm wide, 28 mm high and 15 mm deep, with one changeover contact and a 24 V DC coil. The code reads REL-MR for the miniature relay, 24DC for the coil and 21 for a single changeover. The datasheet gives an input voltage range of 14.4 to 66 V DC around the nominal 24 V DC.
Seven Star LLC supplies the REL-MR-24DC/21 as an independent supplier in Muscat for projects in Oman and the GCC, quoted against the exact part number shown here.
Technical specifications of the REL-MR-24DC/21
| Parameter | Specification |
|---|---|
| Manufacturer / part number | Phoenix Contact REL-MR-24DC/21 (order no. 2961105) |
| Nominal input (coil) voltage | 24 V DC |
| Input voltage range | 14.4 V DC – 66 V DC |
| Typical input current | 7 mA |
| Coil resistance | 3390 Ω ±10 % (at 20 °C) |
| Response / release time | 5 ms |
| Contact configuration | 1 changeover contact |
| Contact material | AgSnO |
| Maximum switching voltage | 250 V AC/DC |
| Limiting continuous current | 6 A |
| Maximum inrush current | 10 A (4 s) |
| Minimum switching current | 10 mA (at 12 V) |
| Interrupting rating, ohmic load | 140 W (at 24 V DC); 20 W (at 48 V DC); 18 W (at 60 V DC); 23 W (at 110 V DC); 40 W (at 220 V DC); 1500 VA (for 250 V AC) |
| Mechanical service life | 2x 107 cycles |
| Test voltage winding/contact | 4 kV AC (50 Hz, 1 min., winding/contact) |
| Ambient temperature (operation) | -40 °C – 85 °C |
| Degree of protection | RT III |
| Switching capacity | 2 A (at 24 V, DC13); 0.2 A (at 110 V, DC13); 0.1 A (at 220 V, DC13); 3 A (at 24 V, AC15); 3 A (at 120 V, AC15); 3 A (at 230 V, AC15) |
| Motor load (UL 508) | 1/4 HP, 240 – 277 V AC (N/O contact); 1/6 HP, 240 – 277 V AC (N/C contact) |
| Dimensions (W x H x D) | 5 x 28 x 15 mm |
How the REL-MR-24DC/21 works
The REL-MR-24DC/21 is a plug-in miniature power relay: a coil that attracts an armature and moves one or two changeover contacts. When the coil is energised within the input range in the table, the common terminal changes from the normally closed to the normally open contact. The coil and the contacts are isolated from each other, with the winding/contact test voltage shown in the table, so a low-voltage control signal can switch a mains-level load. The relay has no socket of its own and is designed to be plugged into a compatible base, for instance a socket module.
The coil draws a typical 7 mA, with a coil resistance of 3390 ohms, and the relay operates in 5 ms and releases in 2.5 ms. Contact material is AgSnO, with a continuous limit of 6 A, 250 V AC/DC and an inrush limit of 10 A for 4 s.
Where the REL-MR-24DC/21 fits in a system
REL-MR relays are the replaceable switching element in many Phoenix Contact relay modules and in customer-built relay sockets. Ordering the relay alone is typical for spares or when a socket is already fitted. Family members differ by coil voltage, number of contacts, contact material and current rating, so the part number decides compatibility with the socket in your panel. Always check that the relay fits the socket series installed.
The REL-MR-24DC/21 is a general-purpose replacement relay where space is tight. If you need two contacts, the 2961192 is wider; for higher continuous current the HC version 2961312 is stronger.
Selection and ordering checklist
- Confirm the coil voltage of the REL-MR-24DC/21 against the control signal and its tolerance.
- Check the number of changeover contacts and the pin pattern of the socket.
- Check the load current and inrush against the contact data in the table.
- Use gold-plated contacts only for low-level signals, and power contacts for loads.
- Confirm the dimensions fit the socket and the DIN-rail space.
- Verify the ambient temperature.
Installation, commissioning and maintenance of the REL-MR-24DC/21
Plug the REL-MR-24DC/21 firmly into a compatible socket, never into a socket designed for a different coil voltage. Check that the relay latches mechanically or sits fully in the retaining clip. Observe the mounting position: the datasheet permits any position. Replace the relay as a whole; do not attempt to clean or open it.
Mechanical life is 2 x 10^7 cycles, and the interrupting rating at 24 V DC is 140 W. Observe the maximum switching capacity table for inductive loads.
Typical applications in Oman and the GCC
In Oman and the GCC, plug-in relays are used in pump and valve controls, compressor panels, HVAC and lighting control and as spare parts in maintenance stores. Keeping a few spare relays per coil voltage shortens repair times considerably.
Narrow relays like this appear in distributed I/O panels, building automation and small control boxes across the GCC.
Comparison with related REL-MR plug-in relays
| Device | Distinguishing data |
|---|---|
| REL-MR-24DC/21 (2961105) | 1 CO, 24 V DC, 6 A, AgSnO, 5 mm wide |
| REL-MR-60DC/21 (2961118) | 1 CO, 60 V DC coil, 6 A, 5 mm wide |
| REL-MR-24DC/21AU (2961121) | 1 CO, 24 V DC, gold contacts, 50 mA |
| REL-MR-24DC/21-21 (2961192) | 2 CO, 24 V DC, 8 A, 12.7 mm wide |
| REL-MR-24DC/21HC (2961312) | 1 CO, 24 V DC, 16 A high continuous current |
| REL-MR-230AC/21-21/MS (2987972) | 2 CO, 230 V AC, test button and LED |
Information to send with an RFQ
- Full part number REL-MR-24DC/21 and quantity.
- Socket or relay module in which it will be used.
- Coil voltage and load details.
- Operating temperature and duty.
- Delivery location and date.
Documents and quotation
Send us the part number REL-MR-24DC/21 and the quantity you need, and we will confirm which official documents are available for this device. Seven Star LLC is an independent supplier in Muscat and quotes for projects across Oman and the GCC; we do not act on behalf of the manufacturer.
Please also tell us the delivery location and required timeline so that availability can be checked before you commit to a project schedule.
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About brand
Phoenix Contact is a German, family-owned manufacturer of electrical connection technology and industrial automation, founded in 1923 in Essen by Hugo Knümann. It began as a sales company, and in 1928 Knümann developed the modular terminal block mounted on a rail, the product the company is still best known for. Phoenix Contact is headquartered in Blomberg, North Rhine-Westphalia.
Seven Star LLC lists Phoenix Contact surge protection, power supplies and safety relays, and sources these components by order number for panel builders and maintenance teams in Oman.
Phoenix Contact company profile
| Founded | 1923, Essen, Germany, by Hugo Knümann, as Phönix Elektro- und Industrie-Bedarfsgesellschaft |
|---|---|
| Headquarters | Blomberg, Germany |
| Ownership | Family-owned (Eisert and Stührenberg families) |
| Key invention | The modular terminal block on a DIN rail, 1928 |
| Product families | CLIPLINE terminal blocks, PCB terminals and connectors, QUINT and TRIO power supplies, relay modules, surge protection, signal conditioners, Ethernet switches and PLCnext controllers |
Milestones
- 1923: Hugo Knümann founds the company in Essen.
- 1928: The first modular terminal block is developed.
- Later: Headquarters move to Blomberg, Ostwestfalen-Lippe.
Phoenix Contact parts listed on this page
The TTC-6-2X1-24DC-UT (order number 2906799) is a surge protection device with screw connection for two 24 V DC signal wires that share a common reference potential. The QUINT-PS/1AC/24DC/10 is a single-phase DIN rail power supply delivering 24 V DC at 10 A. The PSR-SCP-24DC/ESP4/2X1/1X2 (order number 2981020) is a single-channel PSR safety relay for emergency stop and safety door monitoring, with two enabling current paths and plug-in screw terminals.
Phoenix Contact products we list
Ordering Phoenix Contact components: what we need
Phoenix Contact items are ordered by a seven-digit order number together with the type designation, both printed on the side of the module. Send both, plus the quantity. If the number is unreadable, send the type text and a photo. For power supplies, state input voltage, output current and whether the unit runs in parallel or with a redundancy module. For buyers in the GCC replacing an older unit, we check the manufacturer's documentation for the listed successor type.
Facts checked against Phoenix Contact's own company history (phoenixcontact.com), October 2026.
Browse Phoenix Contact products by category: Isolator & Barrier, Power Modules, Automation Accessories.
FAQ
Questions about the Phoenix Contact REL-MR-24DC/21 Plug-in Relay 24 V DC
Answers from our engineering team on installation, compatibility and integration.
01What is the coil voltage?
24 V DC nominal, with an input range of 14.4 to 66 V DC.
02How wide is the relay?
5 mm.
03What is the continuous contact current?
6 A.
04How fast does it switch?
Typical response time 5 ms, release 2.5 ms.
05What is the mechanical life?
2 x 10^7 cycles.
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