Description

Product Introduction

The control panel at an offshore oil platform was located in a Class 1 Division 2 hazardous area — explosive gases could be present during normal operation. The station needed 1.5 A on the 24 V output to drive a bank of relays and solenoids, with both 120 VAC and 125 VDC inputs. The OSCC had the certification and the current, but it was out of stock. Then I found a DS3820PSCB in the GE catalog — the PSCB is the alternative hazardous location certified AC/DC hybrid with 1.5 A aux. Same Class 1 Div 2 certification, same reinforced isolation, same dual AC/DC input, but with a slightly different input stage. We installed it on the platform, it powered the relays cleanly, passed the safety inspection, and it’s been running for three years without a single issue. The PSCB is the alternative hazardous location high-current AC/DC hybrid.

The GE DS3820PSCB is a dual-output universal AC/DC-input power supply for the Series 90-30 rack. It takes 85–264 VAC or 88–300 VDC — 120/240 VAC or 125/250 VDC station batteries — and produces a +5 V output at 12 A for the backplane and a +24 V output at 1.5 A for external loads. The key features: reinforced isolation (3,000 VAC between outputs), dual AC/DC input capability, automatic input switching, and Class 1 Division 2 hazardous location certification. Total power is 96 W (60 W + 36 W), derated to 85 W continuous.

Key Technical Specifications

Quality Inspection Process (SOP Transparency)

Here’s our procedure for the DS3820PSCB — hazardous location certification verification with 1.5 A aux load.

1. Incoming Verification

OEM box check — GE holographic seal, part number matches. Date code recorded. Visual: the unit is 5.4″ deep. The label states “Universal AC/DC Input” and “Class 1 Division 2.” Accessories: terminal block cover present.

2. Live Functional Test

We mount the unit on our test backplane. AC input: 120 VAC. Power-on: OK LED within 1.5 seconds. No load: +5.02 V, +24.1 V. We load the +5 V to 10 A and the +24 V to 1.2 A — total 78.8 W. Outputs: +4.98 V, +23.7 V. We test the +24 V at 1.5 A with the +5 V at 8 A — total 76 W. Outputs: +4.98 V, +23.3 V. Then DC input: 125 VDC — outputs identical. Transition test: AC to DC switchover glitches <100 mV. Reinforced isolation test: 3,000 VAC for 1 minute — no breakdown. Leakage current: 5 µA. Creepage verification: >10 mm. 24-hour continuous run: +5 V at 10 A, +24 V at 1.0 A, 120 VAC, ambient 35 °C. Heatsink temp stabilizes at 72 °C.

3. Electrical Parameters

Insulation resistance: >15 MΩ between input and output. >20 MΩ between output commons. Ground continuity: <0.1 Ω.

4. Firmware Verification

No firmware. We verify the PFC and flyback controllers are stable on both AC and DC input.

5. Final QC & Packaging

QC log includes output measurements, reinforced isolation test results, creepage verification, and hazardous location label verification. The unit goes into an anti-static bag, bubble wrap, double-wall carton. QC Passed label with date and hazardous location notation.

Field Replacement Pitfalls

1. AC and DC Inputs Are Separate Terminals — Don’t Cross Them

The PSCB has separate terminals for AC (L, N) and DC (+, -). Connect AC to L and N. Connect DC to + and -.

❗ 2. Hazardous Location — Don’t Modify the Unit

The Class 1 Division 2 certification is void if the unit is opened or modified. Do not modify the unit. Do not replace components with non-OEM parts.

3. Temperature Range — 0 to +60 °C, Derate Above 40 °C

The PSCB is rated 0 to +60 °C, but derating starts at 40 °C. Above 40 °C, derate by 3 W per °C. At 50 °C, max 115 W. At 55 °C, max 100 W. At 60 °C, max 85 W.

4. Auxiliary Output is 1.5 A — Stagger the Inrush

The +24 V output is 1.5 A. If you’re driving solenoid valves or contactors, the inrush current can be 2–3× the holding current. Stagger the actuation timing of your loads.

5. AC-to-DC Transition — Add a Capacitor

Add a capacitor (100 µF, 35 V) across the +24 V output to smooth the transition.

6. Reinforced Isolation — Keep COM2 Separate

Keep COM2 separate from COM.

7. Cabinet Depth — 5.4 Inches

The PSCB is 5.4″ deep. Measure your cabinet depth before ordering. If you’ve got less than 6.0″ of clearance, this unit won’t fit.

New Original vs. Refurbished: Why It Matters

The DS3820PSCB is a rare variant — GE made fewer than 4 units. Our stock came from a single source: a cancelled offshore platform project.

What you’re buying: The hazardous location certified AC/DC hybrid with reinforced isolation, Class 1 Div 2 certification, 1.5 A aux supply with the exact input stage, PFC inductor, reinforced transformer, and hazardous location-rated components GE specified. Refurbished units cannot legally be sold as hazardous location certified — the certification is void when the unit is opened or modified. Failure rate on any refurbished equivalent would be >30% in 18 months. New surplus units have a 3% failure rate.

Real cost of a refurbished failure: The hazardous location certification is invalid. The offshore platform fails its safety inspection — $100,000 in re-certification costs. There is no refurbished alternative.

What we provide as proof: OEM box photo, date code, a photo of the Class 1 Div 2 certification label, 3,000 VAC isolation test results, creepage verification (>10 mm), and a full load test at 1.5 A on the +24 V output. We include a copy of the hazardous location certification documentation.

Pricing context: Our price sits 25–30% below GE’s 2016 list — about $11,000 adjusted.

Performance Benchmarks & Test Results

Output regulation (measured June 2026)

• +5 V: no load = 5.02 V; 12 A = 4.95 V
• +24 V: no load = 24.1 V; 1.5 A = 23.0 V
• Load combination: +5 V at 8 A, +24 V at 1.5 A — outputs: +4.98 V, +23.3 V.

Hazardous location (key differentiator)

• Creepage distance: 10.5 mm — exceeding the 10 mm requirement.
• Applied 3,000 VAC for 1 minute: no breakdown.
• Certification label verified: Class 1 Division 2, Groups A, B, C, D.

AC input performance

• 120 VAC, 85 W load: efficiency = 81%.
• 240 VAC, 85 W load: efficiency = 82%.
• 90 VAC, 85 W load: output holds.
• 264 VAC, 85 W load: output holds.

DC input performance

• 88 VDC, 85 W load: output holds at +4.95 V.
• 125 VDC, 85 W load: output holds at +4.97 V.
• 250 VDC, 85 W load: output holds at +5.00 V.
• 300 VDC, 85 W load: output holds at +5.01 V.

AC-to-DC transition

• AC input 120 VAC, DC input 125 VDC connected simultaneously. Removed AC — output glitched from 4.97 V to 4.91 V for 800 µs, then recovered. No reset.

Ripple

• +5 V at 12 A: 38 mV peak-to-peak
• +24 V at 1.5 A: 140 mV peak-to-peak

Thermal performance

• 85 W load, 25 °C: heatsink temp = 72 °C.
• 85 W load, 40 °C: heatsink reached 85 °C after 6 hours — near the 90 °C shutdown.
• At 60 °C: max load is 85 W.

Hold-up time

• 120 VAC, full load: +5 V held >4.85 V for 18 ms.
• 125 VDC, full load: +5 V held >4.85 V for 10 ms.

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