Description
Note: Many products are not yet listed. Please contact us for more product information. Our supply channels are constantly expanding, and we currently have 20 stable shared supply channels. Please confirm the model, product, price, and all other necessary information with customer service before placing an order. We offer new, refurbished, and used products, and prices are adjusted according to the year of the item you require.
Product Introduction
When main power distribution breakers lose trip logic, unplanned plant shutdowns follow fast. This ETU VL400 trip unit mates directly into compatible 3VL molded‑case breaker frames, handling line‑side thermal‑magnetic LI protection for general‑purpose power feeds.
Adjustable dial settings let field technicians match overload thresholds to actual load draw, no firmware configuration required. It relies on mechanical‑electronic tripping hardware; calibration drift becomes a risk only after years of sustained high‑temperature cabinet operation (‑though your mileage may vary depending on ambient cabinet ventilation).
3VL9440‑7DC30
3VL9440‑7DC30
3VL9440‑7DC30
Key Technical Specifications
| Parameter | Value |
|---|---|
| Pole Count | 3‑Pole |
| Trip Characteristic | LI Thermal‑Magnetic Line Protection |
| Rated Adjustable Overload (Ir) | 320 A … 400 A |
| Short‑Circuit Instantaneous (II) | 2000 A … 4000 A adjustable |
| Terminal Type | Screw terminal connection |
| Compatible Breaker Series | Siemens 3VL VL400 frame size |
| Compliance Standard | IEC/EN 60947‑2 |
| Operating Ambient Range | ‑25 °C to +60 °C |
| Unit Weight | 1.49 kg |
| Country of Origin | Germany |
Field Application & Technical Pitfalls (The Engineer’s Guide)
Critical Industrial Scenarios
- Main low‑voltage distribution panels for batch manufacturing plants, protecting multi‑motor production bus feeds.
- Auxiliary power distribution inside wastewater treatment facilities, where short‑circuit faults can disable pump banks.
- Commercial facility main feed breakers for large HVAC and lighting load groups.
Technical Pitfalls (Bold Warnings)
- ⚠️ Frame size mismatch: This ETU only fits VL400 frame breakers. Installing it inside a smaller VL250 frame causes incomplete mechanical latching and failed fault tripping.
- ⚠️ Mis‑set overload dial: Operators sometimes set Ir to full 400 A for a 320 A continuous load; sustained over‑rating prevents safe overload trips. Always match dial setting to actual continuous load current.
- ⚠️ Mechanical seating error: If the third locking tab from the left does not fully click into the breaker housing, trip unit linkage will not actuate during a short‑circuit event.
A real‑world field anecdote: One maintenance crew swapped this trip unit during night shift downtime. They skipped visual confirmation of all three locking tabs, closed cabinet doors, and returned the system online. Two weeks later a phase‑to‑ground short hit the distribution bus. The ETU never mechanically triggered, letting fault current persist until upstream fuses cleared. Root cause traced to one un‑clicked locking tab, invisible behind the breaker front cover.
Quality Control (QC) SOP & Transparency
- Inbound Verification: Cross‑reference physical unit label data against OEM packing slip. Inspect housing molding texture, laser mark crispness, and screw terminal condition for counterfeit re‑marking signs; reject units with blurry serial print or sanded casing edges.
- Live Rig Testing: Mount trip unit inside matching VL400 test breaker frame. Execute power‑on mechanical latch validation, verify manual trip button functions under nominal AC supply.
- Parameter Testing: Run insulation resistance check across each pole set at 500 V DC. Confirm dial adjustment travel moves internal cam mechanisms without binding.
- Final QA & Packaging: Wipe external surfaces, place unit inside anti‑static protective bag. Affix internal QC‑passed sticker recording test date and inspector ID, then pack within original OEM or heavy‑duty shock‑absorbent carton.
Frequently Asked Questions (FAQ)
Can this trip unit hot‑swap while the breaker frame remains energized? No. You must fully isolate and rack‑out the breaker before removing or fitting this ETU. Live‑side removal exposes energized bus connections and destroys trip‑unit mechanical alignment.
Will this part work on every 3VL‑series breaker? Well, technically it is for VL400 frame only. It will physically slide into some other frames but will not achieve proper linkage travel. Verify exact frame part‑number against OEM datasheet before ordering.
What warranty coverage comes with new‑surplus stock? Twelve‑month standard warranty applies. Coverage excludes damage from mis‑installation, over‑temperature cabinet conditions, or field‑modification of internal trip dials.
How do I tell genuine OEM stock apart from refurbished re‑marked copies? Genuine units carry sharp, non‑smudged laser serial numbers, uniform plastic molding edges, and factory‑torqued terminal screws. Refurbished counterfeits often show faint sanding marks on casing corners or uneven printed text on labels.
Do I need extra auxiliary accessories with this purchase? Screw terminal hardware ships included with the trip‑unit assembly. Auxiliary switch or shunt‑trip coils are separate orderable items and not part of this part number scope of delivery.
Can I adjust short‑circuit instantaneous trip setting on‑site without special tools? Yes. Accessible front‑panel dials allow both Ir and II adjustments using standard flat‑head screwdriver. After setting, perform visual check to confirm dial indexes align to printed scale markings.
What lead time should I expect if stock runs short? Genuine factory‑origin replenishment can stretch multiple weeks. Surplus on‑hand inventory ships within standard handling windows, subject to final QC pass.
