Phoenix REL-MR- 24AC/21-21 Single Relay
The Phoenix REL-MR- 24AC/21-21 Single Relay (Part No: 2961435 ) offers a 24 V ACnominal input voltage UN, 18.7 V AC ... 37.2 V AC input voltage range, 250 V AC/DC switching voltage, Plug / solder connection method. Manufactured by Phoenix under the Phoenix Single Relay category, this model belongs to the Phoenix REL Series.
| Brand | Phoenix Contact |
| Product Type | Single Relay |
| Model Number | REL-MR- 24AC/21-21 |
Phoenix REL-MR- 24AC/21-21 Single Relay – Technical Specifications
| Specification | Value |
|---|---|
| Product type | Single relay |
| Mechanical service life | 1x 107 cycles |
| Insulation | - |
| Overvoltage category | III |
| Pollution degree | 3 |
| Service life electrical | see diagram |
| Maximum power dissipation for nominal condition | 0.77 W |
| Test voltage (Winding/contact) | 5 kV AC (50 Hz, 1 min., winding/contact) |
| Nominal input voltage UN | 24 V AC |
| Input voltage range | 18.7 V AC ... 37.2 V AC |
| Drive and function | monostable |
| Drive (polarity) | non-polarized |
| Typical input current at UN | 32 mA (at 50 Hz) |
| Typical response time | 3 ms ... 12 ms (depending on phase relation) |
| Contact switching type | 2 changeover contacts |
| Type of switch contact | Single contact |
| Contact material | AgNi |
| Maximum switching voltage | 250 V AC/DC |
| Minimum switching voltage | 5 V (at 10 mA) |
| Limiting continuous current | 8 A |
| Maximum inrush current | 12 A (20 ms) |
| Min. switching current | 10 mA (At 5 V) |
| Interrupting rating (ohmic load) max. | 190 W (at 24 V DC) |
| Connection method | Plug / solder connection |
| Width | 12.7 mm |
| Height | 29 mm |
| Depth | 15.7 mm |
| Degree of protection | RT III |
| Ambient temperature (operation) | -40 °C ... 85 °C |
| Ambient temperature (storage/transport) | -40 °C ... 85 °C |
| Standards/regulations | IEC 60664 |
| Mounting position | any |
| Mains frequency | 50/60 Hz |
| Typical release time range | 2 ms ... 9 ms (depending on phase relation) |
| Coil resistance | 350 Ω ±10 % (at 20 °C) |
| Switching capacity | 2 A (at 24 V, DC13) |
| Motor load according to UL 508 | 1/4 HP, 120 V AC |
Engineered by Phoenix Contact, the REL-MR-24AC/21-21 (Part No: 2961435) is a highly efficient 24VAC Single Relay built for demanding switching operations. With a nominal input voltage of 24 V AC and a broad input range of 18.7 V AC to 37.2 V AC, it ensures dependable performance even in voltage-fluctuating environments. The relay features 2 changeover contacts made of AgNi contact material, offering a maximum switching voltage of 250 V AC/DC and a minimum switching current of 10 mA—making it suitable for both low and high load applications.
It supports a mechanical service life of 10 million cycles and handles a limiting continuous current of 8 A with a maximum inrush current of 12 A (20 ms). With a compact form factor of just 12.7 mm wide, this relay is ideal for space-constrained enclosures. The RT III-rated protection and wide operating temperature range of -40°C to 85°C make it reliable in harsh industrial environments. The test voltage between winding and contact is rated at 5 kV AC (1 min.), providing enhanced insulation and safety. Engineers can integrate it seamlessly using the Plug / Solder connection method. For more options, explore the Phoenix Relay collection or browse all solutions at Phoenix Contact.
The Phoenix REL-MR-24AC/21-21 is widely used in machine control panels, signal isolation modules, industrial relays for PLC I/O expansion, and building automation systems. Maintenance teams appreciate its ease of installation and the long operational lifespan, minimizing downtime and service requirements. The relay’s compact design and low input current of 32 mA at 50 Hz make it suitable for dense control cabinets and embedded systems where space and energy efficiency are critical. It also serves as a reliable reference for engineering students studying relay logic and AC signal control mechanisms. Whether you're retrofitting an existing setup or designing a new control board, this 24VAC Relay offers the durability and performance trusted by automation professionals worldwide.
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