HONEYWELL TK-PRS021 | Power Supply Module for TDC 3000

Description Key Technical Specifications Parameter Specification Model Number TK-PRS021 Input Voltage 90-264 V AC, 47-63 Hz (auto-ranging) Input Current 1.2A max at 120V AC Output Voltage 24V DC ± 2% Output Current 2.1A continuous Output Power 50W maximum Ripple & Noise < 50 mV p-p Efficiency 78% typical at full load Protection Overvoltage (crowbar), overcurrent, thermal shutdown Isolation 1500V AC input-to-output Cooling Convection (no fan) Operating Temp 0°C to 60°C Mounting Plugs into TDC 3000 rack backplane   Product Introduction Here’s the thing about TDC 3000 racks: they’re old, but they’re not dead. The HONEYWELL TK-PRS021 lives in the leftmost slot of your I/O chassis, and when it fails, the whole rack goes dark. No LEDs, no communication, just dead weight. It’s a switching supply, so it runs cooler than the old linear units, but the capacitors still dry out after 10-12 years. You’ll know it’s going when you see intermittent rack resets or “rack fail” alarms that clear themselves. The TK-PRS021 puts out 24V DC at 2.1A—enough for a fully loaded I/O rack, but push it past 80% load and the ripple climbs. Check your configuration before assuming a replacement will behave exactly the same. Sometimes the older racks pulled more current than the nameplate suggests. The unit auto-ranges, so 120 or 240V AC doesn’t matter. That’s one less thing to screw up during a midnight emergency swap. But the connectors on the backplane? Those are another story. They tarnish over time. A new HONEYWELL TK-PRS021 plugged into a corroded backplane won’t solve your problem. You’ll see low voltage at the output terminals even though the module tests fine on the bench.   Installation & Configuration Guide Phase 1: Pre-Installation Lock out the 120/240V AC feed to the rack. Double-check with a multimeter—Honeywell backplanes sometimes have bleed resistors that hold a charge, but not enough to hurt you. Wait 30 seconds anyway. Document which rack slot holds the existing TK-PRS021; it’s usually slot 0 or slot 1 depending on chassis revision. Take a photo of any labeling on the front—some sites sticker the output voltage tolerance or fuse ratings. Phase 2: Removal Loosen the two captive screws on the front panel. They’re quarter-turn, but if they’re corroded, use a flathead carefully. Pull the module straight out. Rocking it bends the backplane pins. Inspect the gold-plated connector fingers. Black spots? That’s oxidation. The new card won’t make good contact if the pins are dirty. Clean the backplane pins with a fiberglass brush or contact cleaner before installing the replacement. Phase 3: Installation Line up the TK-PRS021 with the card guides. Slide it in until the backplane connector seats. You’ll feel resistance—that’s normal. Tighten the captive screws by hand until snug. Don’t overtighten; the plastic standoffs crack. The module has no field wiring—everything runs through the backplane. So no terminal torque specs here. Phase 4: Power-On & Testing Restore AC power. Observe the front-panel LED. Green means output OK. No LED? Check the AC feed and the fuse inside the HONEYWELL TK-PRS021—there’s a slow-blow 2A internal fuse, but it’s not user-serviceable. Once lit, measure 24V DC at the backplane test points (usually TP1 and TP2 on the rack). If it’s below 23.5V under load, either the supply is weak or something in the rack is drawing excessive current. Start pulling I/O cards one by one until voltage recovers. Then you’ve found the short.   Frequently Asked Questions (FAQ) Q: Can I use a generic 24V DIN-rail supply instead of the TK-PRS021? Technically? You could hack it. But the HONEYWELL TK-PRS021 communicates with the rack via a status pin—it tells the controller if the supply is OK. A generic supply won’t have that pinout. The controller will see a “power supply fault” even with perfect voltage. Stick with the original. Q: What’s the typical lifespan of this power supply? Electrolytic capacitors. They’re rated for 2000 hours at 85°C, but in a 40°C control room, you get maybe 10 years. After that, ripple increases and regulation drifts. We see TK-PRS021 failures spike around year 12. If your rack is that old, proactively replace it. Don’t wait for the failure. Q: My TK-PRS021 powers up but the rack is dead. What’s wrong? Check the backplane fuse first. Some TDC racks have a secondary fuse between the TK-PRS021 and the I/O modules. If that’s blown, you’ll have voltage at the supply but nothing downstream. Also verify the 24V rail isn’t shorted—unplug all I/O cards and see if voltage returns. If it does, one of your input cards has a shorted tantalum capacitor. Find it by reinstalling cards one at a time. Q: Is the TK-PRS021 the same as the TK-PRS011? No. The TK-PRS011 is an older, lower-current unit (1.5A). The HONEYWELL TK-PRS021 is the higher-output replacement. They’re physically interchangeable, but the 011 may brown out under heavy load. If your system originally had an 011 and someone swapped in a 021, check the load calculation. The 021 runs cooler, so it’s usually a safe upgrade. Q: Can I hot-swap this module? Bad idea. The backplane carries 120V AC on some pins. Pulling the card under load can arc, pit the connectors, and trip your upstream breaker. Power down the rack. It’s not worth the risk just to save five minutes. Q: The replacement powers up but the controller says “rack fail.” The TK-PRS021 sends a DC OK signal to the controller on pin 32 of the backplane (varies by rack). If that signal doesn’t assert, the controller assumes the rack is dead. Could be a bad connection on that pin or the internal optocoupler in the supply is fried. Measure continuity between the supply’s OK output and the backplane. Open circuit? Swap the card again. 1C31110G01 PLC 1C31110G02 PLC EMERSON 1C31110G03 PLC 1C31113G01 PLC 1C31113G02 EMERSON 1C31113G03 1C31113G04 EMERSON 1C31113G05 PLC Email: [email protected] Phone: 86 15340683922 Sales:Wu Jiedong Our products are guaranteed for 1 year, with new and original production stopped and imported spare parts. All prices listed on the official website are subject to confirmation by contact: Wu Jiedong (manager). Our product: brand new original packaging Our warranty: All new or repaired parts have a 12 month warranty period beginning Our payment: 100% telegraphic transfer of inventory items before shipment, conditions can be proposed! If you have any downtime spare parts that you cannot find, please feel free to call or use email to contact me. If there are issues that the product cannot solve, please contact me. Product prices can be negotiated. Please do not consider contacting me!