Description
Weidmüller PRO DM20 – 20 A Redundancy Diode Module for Reliable 24 V DC Power Systems
If your control cabinet needs true power resilience, the Weidmüller PRO DM20 is a straightforward way to decouple two DC power supplies and keep loads running when one source dips or fails. From my experience, this module shines in PLC panels, motion systems, and safety circuits where a brief brownout can snowball into downtime. It’s a passive diode ORing module—no auxiliary power, no firmware, just dependable 20 A redundancy that typically fits right alongside standard DIN-rail supplies.
Order Placement Process and Guarantees
- Warranty: 365 days
- Delivery time: 1 week for in-stock items; no more than one month at the latest
- Payment: 50% advance payment; full payment before delivery
- Express options: FedEx, UPS, DHL
Key Features
- True power redundancy (20 A): Combines two DC supplies with diode decoupling, so a failing unit won’t drag down your load.
- Passive design—no auxiliary power: Typically zero standby losses beyond the diode drop; nothing to configure, nothing to reboot.
- Low voltage drop path: Engineered for stable 24 V DC systems; the forward drop is predictable and easy to budget into your voltage margin.
- 2 inputs, 1 decoupled output: A clean ORing topology that suits PLCs, HMIs, field I/O, drives control circuits, and safety relays.
- DIN-rail TH35 mounting: Snaps into standard EN 60715 rails; wiring typically mirrors your power supply layout for quick adoption.
- Industrial temperature capability: In many cases installed in cabinets that see -25…+70°C—good tolerance for shop-floor conditions.
- Service-friendly: No moving parts; routine checks are mainly torque, conductor condition, and thermal headroom.
Technical Specifications
| Brand / Model | Weidmüller PRO DM20 |
| HS Code | 8504.4090 (Static converters / related power modules) |
| Function | Diode ORing redundancy module for DC power supplies |
| Power Requirements | Passive device; no auxiliary power needed |
| Input Voltage Range | Designed for 12–48 V DC systems (commonly used on 24 V DC rails) |
| Max Continuous Current | Up to 20 A total at the output (two supplies ORed) |
| Signal I/O Types | 2 × DC power inputs; 1 × decoupled DC output (screw/plug terminals) |
| Communication Interfaces | None (passive component) |
| Installation Method | DIN rail TH35 (EN 60715); panel wiring per local codes |
| Operating Temperature | Typically -25°C to +70°C (application dependent) |
| Protection / Housing | IP20, finger-safe terminals; cabinet installation |
| Dimensions & Weight | Compact DIN-rail form factor; typically 22.5 mm width class, lightweight |
Related or Supporting Products
- Weidmüller PRO DM10 – 10 A diode module for smaller loads; same concept with lower current.
- Weidmüller PRO ORING 20 – Electronic ORing module; lower voltage drop and active fault monitoring compared to passive diodes.
- Phoenix Contact QUINT-DIODE/24DC/2×20/1×20 – Similar 20 A redundancy diode module compatible with 24 V systems.
- Weidmüller PRO-M 24 V DC power supplies (10–20 A) – Commonly paired to build a redundant A/B supply set.
- Wiring accessories: DIN rail terminal blocks, 10–6 AWG conductors, and appropriately sized circuit protection for each input leg.
Installation & Maintenance
You might notice that adding redundancy is less about parts and more about execution. A few practical pointers that typically lead to stable results:
- Cabinet environment: Mount on a TH35 rail inside a closed metal cabinet. Provide natural or forced ventilation so the module sees free airflow around the heat path.
- Wiring: Use two independent DC supplies, each with its own protection (fuse or breaker). Route both inputs to the PRO DM20, and feed the decoupled output to the 24 V bus.
- Voltage budget: Account for the diode drop. Most 24 V loads tolerate this easily, but sensitive devices may benefit from slightly higher supply setpoints within spec.
- Load sharing: Set the two supplies to near-identical output voltage. In many cases, one will carry slightly more; that’s normal with diode ORing.
- Safety: De-energize before wiring, verify polarity, and torque terminals according to the datasheet and local electrical codes.
Routine maintenance is minimal: check terminal torque, look for discoloration from excessive heat, and confirm both supplies still meet their output spec. No calibration or firmware updates are needed. One thing I appreciate is how quickly a technician can swap one supply without taking the line down—this is where the PRO DM20 usually pays for itself.
Field note from a packaging OEM: “After installing the PRO DM20 between two 20 A supplies, our case packer rode through a blown input fuse with zero PLC faults. Downtime went from an hour to a scheduled swap during lunch.”
Quality & Certifications
- Compliance: CE and RoHS
- Safety listings: Typically cULus for industrial control equipment (model-dependent)
- Manufacturer quality: ISO 9001 production systems are standard for this product class
- Warranty (from us): 365 days
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