Phoenix Contact REL-MR-24AC/21-21/MS Single Relay

Technical Overview

24V AC plug-in miniature relay with 2 changeover AgNi contacts, 8A continuous current, and -40°C to 70°C operating temp.

Key Features

Integrated test button for detectable manual operation, aiding commissioning and fault-finding.
Integrated status LED provides instant visual confirmation of the relay's energization state.
Mechanical switch position indicator clearly shows contact status without live testing.
Features 2 changeover contacts (DPDT) with Silver-Nickel (AgNi) material for versatile switching and reliability.
Wide coil voltage tolerance of 18.7 V AC to 34.8 V AC accommodates supply fluctuations.
Corrosive gas tested to ISA-S71.04 G3 Harsh Group for challenging environmental conditions.
Plug-in design facilitates quick and easy replacement, minimizing downtime.

Technical Specification Matrix

Parameter	Value
Nominal Input Voltage (Coil)	24 V AC
Input Voltage Range (Coil)	18.7 V AC - 34.8 V AC
Mains Frequency	50/60 Hz
Typical Input Current at UN	32 mA
Contact Type	2 changeover contacts (DPDT)
Contact Material	AgNi (Silver Nickel)
Maximum Switching Voltage	250 V AC/DC
Limiting Continuous Current	8 A
Maximum Inrush Current	16 A (20 ms)
Interrupting Rating (Ohmic Load)	2000 VA at 250 V AC
Test Voltage (Winding/Contact)	5 kV AC (50 Hz, 1 min.)
Test Voltage (Contact/Contact)	2.5 kV AC (50 Hz, 1 min.)
Maximum Power Dissipation	0.77 W
Typical Response Time	3 ms - 12 ms
Mechanical Service Life	5 x 10^6 cycles
Operating Temperature	-40 °C to 70 °C
Storage Temperature	-40 °C to 85 °C
Connection Method	Plug / solder connection
Physical Weight (kg)	0.02
Dimensions L x W x H (cm)	2.5 x 1.27 x 2.9

Industrial Applications

1. Industrial Machine Control Panels

This relay is ideal for switching 24 V AC control circuits within industrial machine control panels. Its dual changeover contacts and 8A continuous current rating make it suitable for various control functions.

Problem Solved

Provides reliable and versatile switching for control signals and low-power loads, ensuring precise operation and safety interlocking within machinery.

24 V AC control8A switchingDPDT contactsMachine control

2. Motor Starter and Contactor Pilot Circuits

With a maximum inrush current capacity of 16 A (20 ms), this miniature relay can effectively manage the inductive loads found in motor starter and contactor pilot circuits, preventing contact welding and extending operational life.

Problem Solved

Safely handles high inrush currents typical of inductive loads, protecting control circuitry and ensuring long-term reliability of motor starting systems.

16A inrush currentMotor controlContactor pilotInductive loads

3. Building Automation and HVAC Systems

The wide coil voltage tolerance (18.7 V AC - 34.8 V AC) and -40 °C to 70 °C operating temperature range make it suitable for reliable operation in building automation and HVAC systems, where environmental conditions can vary and supply fluctuations may occur.

Problem Solved

Ensures consistent and reliable operation of building automation and HVAC components despite potential power supply fluctuations and broad ambient temperature variations.

HVAC controlBuilding automationWide voltage toleranceTemperature range