Key Technical Specifications
| Parameter | Value |
|---|---|
| Output Voltage | 24 V DC |
| Output Current | 40 A |
| Rated Power | 960 W |
| Input Voltage | 100-240 V AC |
| Technology | SFB (Selective Fuse Breaking) |
| Boost Current | Power Boost for heavy loads |
| Mounting | DIN Rail |
| Temp Range | -25°C to +70°C |
| Derating | Starts > 60°C |
Product Introduction
I’ve seen too many power supplies trip breakers during motor startups because they couldn’t handle the inrush. The QUINT-PS-100-240AC/24DC/40 (2938879) fixes that with SFB technology, pushing 6x rated current for 12ms to selectively trip standard breakers without killing the whole bus. It’s a 960W workhorse that keeps the rest of your control panel alive when one branch faults.Engineers stick with this unit because the Power Boost function reliably starts heavy loads like valves and contactors without voltage sag. I’ve run these in panels hitting 55°C ambient, and they keep humming right up to the 60°C derating point. Just make sure you have airflow; these things dump heat when pushing 40A continuously.
Quality SOP & Tech Pitfalls
The Lab Report:
I don’t trust “new” labels blindly. Every 2938879 gets a visual check for pin corrosion or case cracks. Then it goes on the test rack: 240V AC in, 40A resistive load out, monitored for 2 hours with a Fluke 115 to check ripple and thermal stability. We log the firmware and serial before anti-static sealing.The Engineer’s Warning:
Don’t ignore the derating curve. I watched a guy stuff three of these in a sealed NEMA 12 box with no fan; they tripped on thermal overload at 45°C ambient. Also, verify your input breaker sizing. SFB needs a B or C curve breaker to work right; a D curve might not trip fast enough to isolate the fault, defeating the whole purpose of the tech.
Installation & Configuration Guide
- Pre-Installation: ⚠️ Lockout/Tagout. Wait 5 minutes for caps to discharge. Take a photo of the old wiring and DIP switch settings before touching anything.
- Removal: Label every wire with tape. Release the DIN clip with a flathead; don’t pry the plastic housing or you’ll crack it.
- Installation: Copy the DIP switch settings exactly. This is where 90% of “DOA” complaints come from. Slide the QUINT-PS-100-240AC/24DC/40 onto the rail until it clicks. Torque terminals to spec.
- Power-On: Apply AC input. Watch the “DC OK” LED. If it blinks or stays off, check input voltage and output short circuits immediately. Download your logic and verify the 24V rail under load.
Compatible Replacement Models
| Status | Model | Notes |
|---|---|---|
| ✅ Drop-in | QUINT-PS-100-240AC/24DC/40 (2938879) | Direct match. Same footprint, same SFB. |
| ⚠️ Software Compatible | QUINT4-PS/1AC/24DC/40 | Newer gen. Same specs, but check DIN rail height; might need adapter. |
| ❌ Hardware Mod | TRIO-PS-3AC/24DC/40 | 3-Phase input. Requires rewiring input side. Only if you have 3-phase available. |
Frequently Asked Questions
Can I parallel two of these for 80A?
Yes, but you need the active redundancy module (QUINT-ORING). Don’t just tie the outputs together; you’ll get circulating currents and one supply will try to eat the other.Is this the same as the old QUINT-PS/1AC/24DC/40?
Functionally, yes. The 100-240AC/24DC/40 is the updated part number with wider input range and SFB tech. Check your panel cutout; the depth might differ slightly.Why does my breaker trip instantly on startup?
You likely have a short or a massive inrush load that exceeds the SFB window. Check your load wiring first. If it’s a transformer, ensure it’s not saturated. SFB is smart, but it’s not magic.Do I need to adjust the output voltage?
It comes set to 24V. You can trim it up to 28.5V if you have long cable runs causing drop, but verify your load tolerance first. I’ve fried 24V relays because someone cranked it to 29V “just to be sure.”What happens if I lose one phase on the input?
This is a single-phase unit. If you’re on a 3-phase panel, just pick one leg and neutral. If you meant a 3-phase QUINT, those can handle single-phase loss, but this specific 2938879 is strictly 1-phase input.
