Key Technical Specifications
- Product Model: PSMU-350-3
- Manufacturer: PTM
- Product Type: Industrial Power Supply Module
- Output Voltage: 24 VDC (Adjustable)
- Output Power: 350 Watts
- Input Voltage: 100-240 VAC (Auto-ranging)
- Protection: Overload, Over-voltage, Short-circuit
- Mounting: Standard 35mm DIN Rail
- Cooling: Forced Air / Fan Cooled
- Operating Temp: -10°C to +60°C
- Isolation: Input-Output Electrical Isolation
- Compliance: CE, UL (Verify specific marking on unit)
Product Introduction
PTM PSMU-350-3 is a 350W industrial power supply designed for DCS and PLC control cabinets. It converts standard AC mains to a stable 24V DC rail for controllers, I/O modules, and field instruments.This module features active overload protection and electrical isolation to prevent ground loops. Field units often show minor cosmetic wear on the DIN clip, but internal capacitors are tested for ripple voltage under full load. (We’ve seen units fail due to fan dust buildup, not electronics.)
Installation & Configuration Guide
Preparation (10 min)
Verify input voltage matches site supply. Measure 24V DC output on a bench supply if replacing a failed unit. Gather insulated screwdrivers and torque driver.Removal (5–10 min)
⚠️ LOCKOUT/TAGOUT: Disconnect all AC and DC sources. Wait 60 seconds for capacitor discharge. Verify zero energy with a multimeter. Remove DC output wires first, then AC input. Release DIN rail latch.Installation (10 min)
Snap PSMU-350-3 onto DIN rail. Torque terminal screws to 0.8 Nm. Connect ground wire first. Ensure 50mm clearance above/below for airflow. (The fan intake is on the bottom; blocking it kills the unit in 3 months.)Power-On & Test (10 min)
Apply AC input. Verify green “DC OK” LED illuminates. Measure output voltage at load terminals (not just at PSU). Confirm 24.0V ±5%. Check fan operation audibly.
Troubleshooting Quick Reference
| Symptom | Probable Cause | Action |
|---|---|---|
| No Output / LED Off | Input fuse blown or AC loss | Check input voltage. Measure fuse continuity. |
| Output Voltage Low | Overload or capacitor aging | Measure load current. Disconnect load to test. |
| Intermittent Faults | Loose terminal or fan failure | Re-torque all connections. Inspect fan blades. |
| Over-voltage Trip | Feedback loop open | Check sense wire connections (if applicable). |
| Excessive Noise | EMI or grounding issue | Verify ground wire gauge and routing. |
Dimensions, Mounting & Wiring Notes
- Dimensions: Approx. 110mm (H) x 125mm (W) x 100mm (D)
- Mounting: 35mm DIN Rail (TS-35)
- Terminals: Screw-type, rated for 14-2 AWG
- Wiring Note: Use ferrules on stranded wire. Do not tin wires before screw terminals.
- Clearance: Min. 50mm vertical airflow, 20mm horizontal.
FAQ
Is PSMU-350-3 compatible with Siemens S7-300 racks?
Yes, as a general 24V DC source. It does not provide the specific backplane signaling of a Siemens PS307, so use it for external load power, not CPU backplane power.I replaced it but the LED is still red. What now?
Check the load side. A shorted field device or I/O card will trip the protection immediately. Disconnect all output wires and power up. If LED turns green, the PSU is fine; your load is shorted.Can I use this for a 48V application?
No. PSMU-350-3 is fixed at 24V DC. Do not attempt to modify internal potentiometers beyond the trim range.What is the lead time for bulk orders?
Current stock ships same-day. Bulk requests (>10 units) require 3-5 days for batch testing and documentation.Does it come with a test report?
Yes. Every unit includes a printed QC sheet showing output ripple, voltage accuracy, and protection trip points measured during the 24-hour load test.I heard a clicking sound before it died. Is this normal?
No. Clicking usually indicates relay chatter or capacitor venting. If you smell ozone or burnt plastic, do not re-energize. Return for analysis.Is this new or refurbished?
This unit is refurbished and tested. We replace electrolytic capacitors and fans as part of the SOP. Cosmetic scratches on the casing are possible; electrical performance is verified to OEM spec.
