Phoenix Contact PLC-RSC-24DC/21 Relay Module, 1 Changeover, 24 V DC
Overview
The Phoenix Contact PLC-RSC-24DC/21 (item number 2966171, catalogue designation PLC-RSC- 24DC/21) is a relay module from the PLC-INTERFACE range. It consists of a PLC-BSC…/21 basic terminal block with screw connection and a plug-in miniature relay with a power contact, assembled for mounting on an NS 35/7.5 DIN rail. The Phoenix Contact PLC-RSC-24DC/21 provides one changeover contact controlled by a 24 V DC input and is only 6.2 mm wide, which makes it one of the most widely used interface relays between PLC outputs and field devices in industrial cabinets.
Seven Star LLC supplies the Phoenix Contact PLC-RSC-24DC/21 to panel builders, system integrators and maintenance teams in Oman and across the GCC. From our office in Muscat, we help customers standardise their interface relays for control, safety and marshalling panels.
Role of an Interface Relay
As general engineering background, a PLC digital output card is designed for low currents and must be protected from inductive loads, high voltages and field wiring faults. An interface relay such as the Phoenix Contact PLC-RSC-24DC/21 decouples the control system from the field: the PLC drives the relay coil at 24 V DC, while the relay contact switches the actual load, for example a contactor coil, a solenoid valve, an indicator lamp or an alarm horn. Phoenix Contact specifies safe isolation between the coil and the contact side, with a test voltage of 4 kV AC (50 Hz, 1 min) between winding and contact and a rated impulse withstand voltage of 6 kV.
The input circuit of the Phoenix Contact PLC-RSC-24DC/21 already includes reverse polarity protection and a freewheeling diode for interference suppression, and a yellow LED shows when the coil is energised. The drive is monostable and polarized, the typical input current at 24 V DC is 9 mA, and typical response and release times are 5 ms and 8 ms.
Contact Rating
The changeover contact of the Phoenix Contact PLC-RSC-24DC/21 is a single power contact made of AgSnO. The maximum switching voltage is 250 V AC/DC, the limiting continuous current is 6 A and the maximum inrush current is 10 A for 4 seconds. The minimum switching values are 5 V at 100 mA and 10 mA at 12 V, so the relay is intended for power loads rather than very low signal levels. For ohmic DC loads, the interrupting rating is 140 W at 24 V DC, 20 W at 48 V DC, 18 W at 60 V DC, 23 W at 110 V DC and 40 W at 220 V DC, and 1500 VA at 250 V AC.
For control duty, the switching capacity of the Phoenix Contact PLC-RSC-24DC/21 is 3 A at 24, 120 and 230 V for AC15 and 2 A at 24 V, 0.2 A at 110 V and 0.1 A at 220 V for DC13. As general guidance, inductive DC loads above these values should be suppressed or switched through a contactor. A 4 A gL/gG NEOZED output fuse is listed in the data sheet, and the conditional short-circuit current is 200 A.
Key Features
- Slim 6.2 mm design with one changeover contact.
- Plug-in miniature relay with RT III sealed construction.
- Safe isolation between coil and contact side, 4 kV AC test voltage.
- Integrated input circuit with reverse polarity protection and freewheeling diode.
- Switching up to 250 V AC/DC and 6 A limiting continuous current.
- Functional plug-in bridges and connection to system cabling through the V8 adapter.
- Mechanical service life of 2 × 107 cycles.
- Operating temperature −40 to +70 °C (observe derating) and ISA-S71.04 G3 corrosive gas test.
Applications in Oman and the GCC
The Phoenix Contact PLC-RSC-24DC/21 is typically installed in rows beside PLC or DCS cabinets to interface digital outputs with motor control centres, valve actuators, pump starters, beacons and annunciators. In oil and gas facilities, water treatment plants, power stations and building management systems in Oman and the GCC, the compact width allows dozens of relays on a short rail section, and the plug-in bridges speed up common-potential wiring. The ISA-S71.04 G3 Harsh Group corrosive gas test listed by Phoenix Contact is a useful reference for installations exposed to industrial atmospheres, while the shipbuilding approval supports marine use within its conditions.
Seven Star LLC also supplies safety and protection devices that are often used in the same panels, such as the Phoenix Contact PSR-SCP-24DC/ESP4 safety relay, the Pilz PNOZ s4 safety relay and the ABB TA25DU6.5 thermal overload relay for motor protection.
Technical Specifications
The following data for the Phoenix Contact PLC-RSC-24DC/21 is taken from the Phoenix Contact product data sheet for item 2966171.
| Parameter | Specification |
|---|---|
| Item number | 2966171 |
| Product family | PLC-INTERFACE relay module |
| Nominal input voltage | 24 V DC; range 18.5 to 33.6 V DC (20 °C) |
| Typical input current | 9 mA |
| Response / release time | 5 ms / 8 ms typical |
| Protective circuit | Reverse polarity protection, freewheeling diode |
| Operating voltage display | Yellow LED |
| Contact type | 1 changeover contact, single power contact, AgSnO |
| Maximum switching voltage | 250 V AC/DC |
| Limiting continuous current | 6 A |
| Maximum inrush current | 10 A (4 s) |
| Minimum switching | 5 V (100 mA); 10 mA (12 V) |
| Switching capacity | 3 A at 24/120/230 V (AC15); 2 A at 24 V, 0.2 A at 110 V, 0.1 A at 220 V (DC13) |
| Interrupting rating (ohmic) | 140 W at 24 V DC; 40 W at 220 V DC; 1500 VA at 250 V AC |
| Insulation coil/contact | 250 V rated; 6 kV impulse; 4 kV AC test (1 min) |
| Mechanical service life | 2 × 107 cycles |
| Dimensions (W × H × D) | 6.2 × 80 × 94 mm |
| Connection | Screw, M3; 0.2 to 2.5 mm² single ferrule |
| Degree of protection | Relay RT III; relay base IP20; installation location IP54 or higher |
| Ambient temperature | −40 to +70 °C operation; −40 to +85 °C storage |
Installation Notes
Snap the Phoenix Contact PLC-RSC-24DC/21 onto an NS 35/7.5 DIN rail. Phoenix Contact notes that a PLC-ATP separating plate must be installed between identical terminal blocks in adjacent modules for voltages above 250 V (L1, L2, L3), with potential bridging carried out using FBST 8-PLC or FBST 500 bridges. Use copper conductors approved for at least 75 °C, as stated in the UL data. The installation location should provide IP54 protection or higher.
Selection and Maintenance Notes
When specifying the Phoenix Contact PLC-RSC-24DC/21, check three points as general practice: the coil voltage must match the PLC output (24 V DC here), the contact rating must cover the load under its utilisation category, and the minimum switching values must suit the circuit. Because the relay is pluggable, a worn relay can be exchanged without rewiring the base, which shortens maintenance time during shutdowns. Standardising on the Phoenix Contact PLC-RSC-24DC/21 for 24 V DC interface duties also reduces the number of spare part types a site needs to keep. For mixed voltages, other coil versions of the same PLC-INTERFACE range exist, and our team can help confirm the right variant from the Phoenix Contact data.
How to Order
To request a quotation for the Phoenix Contact PLC-RSC-24DC/21, contact the Seven Star LLC automation team with your quantity and project details. We provide model selection support from Muscat, share the manufacturer data sheet and support control panel work across Oman and the GCC.
- Datasheet Phoenix Contact PLC-RSC- 24DC/21 (2966171) Product Data Sheet Download
Phoenix Contact parts listed on this page
Three product groups are represented. 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.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.Browse Phoenix Contact products by category: Isolator & Barrier, Power Modules, Automation Accessories.
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