DS4820R20 | Replace DS4820R10 Direct

Description

Product Introduction

The DS4820R20 is the next-generation power supply for the Mark V platform—same 20A output as the R10, but with a redesigned thermal path and a few extra features. It’s still the heart of the rack, converting 120/240 VAC into 24 VDC for the CPU and I/O modules. But this revision runs cooler, holds up longer on power loss, and includes internal OR-ing diodes for seamless redundancy without external wiring.

Compared to the DS4820R10, the R20 brings a handful of targeted improvements: the cooling fan was upgraded to a higher-flow model (45 CFM vs. 35 CFM), the heatsink was enlarged, and the hold-up time was extended from 25ms to 30ms. The power factor correction was also tuned for better performance at low-line (100VAC) operation. The terminal assignment is identical—it’s a direct drop-in. No firmware changes required. If you’re running redundant supplies, this revision simplifies the wiring—no external diode modules needed.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: What’s the difference between the R20 and the R10?
The R20 has a redesigned thermal path (larger heatsink, higher-flow fan) that runs about 5°C cooler at full load. The hold-up time is 30ms vs. 25ms—that 5ms can make the difference between riding through a power dip vs. a CPU reset. The R20 also includes built-in OR-ing diodes for redundancy, so you don’t need external diode modules when running two supplies in parallel. The terminal assignments are identical, so it’s a direct swap.

Q: Can I run two R20 supplies in parallel for redundancy?
Yes—the R20 has internal OR-ing diodes, so parallel operation is plug-and-play. Connect the DC outputs together (+24V to +24V, 0V to 0V) and feed the AC inputs from separate breakers or UPS feeds. Each supply will share the load roughly equally (within 5%). If one fails, the other takes the full load seamlessly. The blue “Redundancy Active” LED will light when both supplies are present and sharing. GE recommends each supply be sized for 50% of the total load—so for a rack drawing 15A, a single R20 is fine (redundancy optional).

Q: The blue Redundancy LED is off, even though two supplies are installed. What’s the likely cause?
The blue LED indicates that both supplies are present and the internal OR-ing diodes are active. If it’s off, one of the supplies may not be seated correctly or the AC input to one supply may be missing. Also, if the load is less than 5A, the LED might not light—it’s designed to activate only when both supplies are contributing at least 2A each. If both supplies are on and the load is low, the LED may stay off. Check the input power to each supply with a multimeter.

Q: The Fault LED is red, but the DC OK LED is green. What’s happening?
Green DC OK means the 24V output is within spec. Red Fault indicates an internal warning—typically overtemperature (fan failure or blocked airflow) or an input voltage out of range (below 85VAC or above 265VAC). The R20 has a temperature sensor on the heatsink—if it hits 80°C, it’ll flag a fault but keep running (it shuts down at 85°C). Check the fan—it’s user-replaceable (92mm x 25mm, 12V DC). If the fan is stalled, the supply will derate and eventually shut down.

Q: What’s the hold-up time, and why is it better on the R20?
Hold-up time is how long the supply maintains 24V output after AC input is lost. The R20’s 30ms hold-up is 5ms longer than the R10’s. This matters if your UPS has a slow transfer time (e.g., 15-20ms). With a 30ms hold-up, even a slow UPS (or a momentary grid dip) won’t cause the CPU to reset. If your grid is unstable, the R20’s extra 5ms is a welcome buffer. GE achieved this by increasing the input capacitor bank.

Q: The fan is loud and runs continuously at full speed. Is that normal?
The R20’s fan is temperature-controlled and has a higher flow rate (45 CFM) than the R10’s fan (35 CFM). At high loads (>300W), it ramps to full speed—which is noticeable. If it’s running at full speed at idle, the temperature sensor may be faulty or the heatsink is blocked with dust. Blow out the unit with compressed air (hold the fan blade to prevent overspeed). If the fan speed doesn’t change with load, the fan control circuit may be dead—the fan defaults to full speed as a fail-safe.

Q: Can I use the R20 on a 100V AC supply?
Yes—the input is auto-ranging from 100-240VAC. At 100VAC, the input current is higher (about 6A at full load vs. 3A at 240VAC). Make sure your branch breaker is rated for at least 10A. Also, at 100VAC, the hold-up time drops to about 22ms—still better than the R10 at 100VAC (which drops to 18ms). If you’re in a 100V region (e.g., Japan), the R20 is a better choice for stability.

Q: The Overload LED is amber. What does that mean?
Amber Overload LED indicates the supply is drawing more than its continuous rating (20A). At loads between 20A and 24A, it’ll light amber and continue running—but the output voltage may droop (down to 22V). If the load exceeds 24A, the supply enters foldback current limiting (output drops to about 12V, and the LED flashes). Check your rack’s total load—a fully populated Mark V rack with 10 I/O modules and a CPU can draw up to 18A, so you should be fine. If you’re above 20A, consider adding a second supply in parallel.

Q: Can I hot-swap the R20 while the rack is powered?
The R20 supports hot-swapping when used in a redundant configuration (two supplies in parallel). In a single-supply configuration, pulling the supply will immediately shut down the entire rack—a guaranteed turbine trip. If you have redundant supplies, you can pull one while the other carries the load—the OR-ing diodes are internal, so no external wiring changes are needed. Just verify the load is within the single supply’s capacity (20A). If the load is 18A, it’s safe. If it’s 22A, you’ll trigger the overload on the remaining supply.

Q: What’s the expected lifespan of the R20?
The electrolytic capacitors are rated for 12,000 hours at 85°C—about 1.4 years at full load in a hot environment. In a 40°C cabinet, the lifespan extends to about 18-22 years (capacitor lifetime doubles for every 10°C drop). The fan is rated for 60,000 hours at 40°C (about 6.8 years). Replace the fan every 5-7 years proactively if the cabinet runs warm. The R20’s larger heatsink and higher-flow fan help the capacitors run cooler, extending their life vs. the R10.

Q: What’s the lead time for a surplus R20?
We keep 4-6 units in stock. Domestic: 2-3 business days ground, overnight if ordered by 2 PM EST. International: 5-7 days via DHL, with customs potentially adding 1-3 days. This board is not ITAR-controlled, so we can ship to most countries without an export license. We include a GE certificate of origin and commercial invoice with every shipment. If you need the unit urgently for a critical outage, we can arrange expedited shipping—contact us directly.

NI PCI-8512
TRICONEX 3401
FOXBORO 130M-N4
FOXBORO 870ITEC-AYFNZ