SIEMENS B43570-S4338-Q3 – Aluminum Electrolytic Capacitor, Screw Terminal, Long-Life | EPCOS / TDK B43570 Series
Engineering Background
The B43570 series was originally developed under the SIEMENS EPCOS brand and is now continued under TDK Electronics (TDK EPCOS). Designed for demanding power electronics applications, this series has accumulated decades of field-proven reliability in industrial drives, UPS systems, and DC-link bus filtering. The B43570-S4338-Q3 represents the high-voltage, high-capacitance segment of this family, engineered specifically for environments where ripple current handling, thermal stability, and service life are non-negotiable.
Product Positioning
This capacitor is the preferred choice for procurement engineers sourcing DC-link and bulk energy storage components for industrial inverters, servo drives, and power conversion equipment. Its screw-terminal construction ensures low-resistance, vibration-resistant connections in high-current bus architectures. Konmask.com stocks this part with full traceability documentation to support MRO, OEM line replenishment, and capital equipment refurbishment projects.
Complete Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | B43570-S4338-Q3 |
| Manufacturer | SIEMENS EPCOS / TDK Electronics |
| Series | B43570 |
| Capacitance | 3300 µF |
| Rated Voltage (DC) | 400 V |
| Capacitance Tolerance | -10% / +30% (M) |
| Leakage Current (max) | ≤ 0.06 × C × U (µA), after 5 min |
| Dissipation Factor (tan δ) | ≤ 0.15 at 100 Hz, 20°C |
| ESR (Equivalent Series Resistance) | Refer to datasheet curve at 100 Hz |
| Ripple Current (max, 85°C) | Refer to B43570 series datasheet |
| Operating Temperature Range | -25°C to +85°C |
| Rated Temperature | 85°C |
| Endurance (at rated conditions) | 2000 hours at 85°C |
| Terminal Type | Screw terminal (M6) |
| Mounting Style | Snap-in / Chassis mount with screw terminal |
| Case Diameter | Approx. 75 mm (refer to datasheet) |
| Case Height | Approx. 115 mm (refer to datasheet) |
| Weight | ~1800 g |
| Electrolyte Type | Non-solid aluminum electrolytic |
| Polarity | Polarized |
| RoHS Compliance | RoHS 2 compliant |
| Country of Origin | Germany / EU |
Proven Application Environments
- Industrial AC/DC Drives & Servo Amplifiers — DC-link bus capacitor bank for SIEMENS SINAMICS, ABB ACS, Danfoss VLT, and equivalent drive platforms
- UPS & Energy Storage Systems — Bulk energy buffer in double-conversion UPS topologies requiring high capacitance at 400 V DC bus
- Welding Equipment — Energy storage and smoothing in resistance and MIG/MAG welding power supplies
- Renewable Energy Inverters — DC-link filtering in solar string inverters and wind turbine converters
- Railway & Transportation Power Electronics — Auxiliary power supply filtering in rolling stock and trackside equipment
- Industrial Power Supplies (SMPS) — Output bulk capacitance in high-power switch-mode power supplies
- Motor Control Centers (MCC) — Capacitor bank replacement and MRO replenishment in existing panel assemblies
Engineering Advantages
- High Capacitance × Voltage Product — 3300 µF at 400 V delivers 264 J of stored energy, suitable for demanding transient absorption requirements
- Screw Terminal Construction — M6 screw terminals provide low-contact-resistance, mechanically secure connections rated for high ripple current without solder joint fatigue
- Long Operational Life — 2000-hour endurance at 85°C; extended life projections available via Arrhenius model at lower operating temperatures
- Wide Temperature Range — -25°C to +85°C operation covers both cold-start and continuous high-ambient industrial environments
- EPCOS / TDK Pedigree — Manufactured to IEC 60384-4 and SIEMENS internal quality standards; full PPAP and material traceability available on request
- Direct OEM Cross-Reference — Drop-in compatible with EPCOS B43570-S4338-Q3; no derating required when replacing like-for-like
System Architecture & Signal Flow
In a typical industrial drive DC-link architecture, the B43570-S4338-Q3 is positioned between the rectifier bridge output and the IGBT inverter stage. The capacitor performs three critical functions:
- Bulk Energy Storage — Absorbs rectified AC ripple and provides instantaneous energy during load transients, preventing DC bus voltage collapse during motor acceleration
- Ripple Current Filtering — Attenuates switching-frequency ripple generated by the PWM inverter, reducing EMI and protecting upstream rectifier components
- Overvoltage Buffering — Absorbs regenerative braking energy returned from the motor, clamping DC bus voltage within safe operating limits
Typical bus configuration: capacitors are paralleled in banks to achieve target capacitance and ripple current ratings. Ensure bus bar inductance is minimized (<50 nH recommended) and that each capacitor is individually fused or protected by a pre-charge circuit to prevent inrush damage at power-on.
Sourcing & Quality Verification
- Authorized Distribution Chain — Konmask sources B43570-S4338-Q3 through verified industrial distribution channels with full lot traceability
- Incoming Inspection — Each unit undergoes capacitance, ESR, and leakage current verification against datasheet limits prior to dispatch
- Packaging Integrity — Original OEM packaging or equivalent ESD-safe anti-static packaging; units are not repackaged or relabeled
- Documentation Available — Certificate of Conformance (CoC), manufacturer datasheet, and test reports available upon request for regulated procurement environments
- Counterfeit Mitigation — Physical inspection includes date code verification, terminal finish inspection, and capacitance/ESR cross-check against known-good reference units
Procurement Process
- Submit RFQ — Contact support@konmask.com with quantity, required delivery date, and any documentation requirements (CoC, MSDS, RoHS declaration)
- Quotation & Lead Time Confirmation — Konmask will confirm stock availability, unit pricing (volume breaks available for qty ≥ 5), and estimated ship date within 1 business day
- Order Placement — Place order via Konmask.com checkout or via PO for approved corporate accounts; T/T, L/C, and trade assurance payment terms available
- Quality Documentation — CoC and test report issued with shipment; additional PPAP documentation available for OEM customers on request
- Shipping & Logistics — DHL Express, FedEx International Priority, and sea freight options available; export packing for international shipments included
Technical FAQ
Q: Can the B43570-S4338-Q3 be used in a 380 V AC three-phase drive application?
A: Yes. In a standard three-phase 380 V AC drive, the rectified DC bus voltage is approximately 537 V peak. However, the DC-link capacitor typically operates at a nominal 540–600 V DC bus in 400 V AC systems. The B43570-S4338-Q3 is rated at 400 V DC and is NOT suitable for direct use in 400 V AC three-phase drives without derating analysis. Verify your actual DC bus voltage before specifying this part.
Q: What is the expected service life at 70°C operating temperature?
A: Using the Arrhenius rule-of-thumb (life doubles for every 10°C reduction), at 70°C the projected life is approximately 8000 hours (4× the 2000-hour rating at 85°C). Actual life depends on ripple current loading and applied voltage.
Q: Is this part interchangeable with the EPCOS B43570-S4338-Q3?
A: Yes. SIEMENS EPCOS and TDK EPCOS B43570-S4338-Q3 share identical specifications. The SIEMENS branding reflects legacy production; current production is under TDK Electronics. Electrical and mechanical dimensions are identical.
Q: What pre-charge circuit is recommended?
A: A series NTC thermistor or resistor-relay pre-charge circuit limiting inrush to <10 A is recommended. Pre-charge time should allow bus voltage to reach ≥90% of nominal before the main contactor closes. Consult your drive OEM's application note for specific pre-charge requirements.
Q: Can multiple units be paralleled?
A: Yes. Parallel operation is standard practice in high-capacitance DC-link banks. Ensure matched capacitance values (within ±5%) and symmetric bus bar layout to ensure equal current sharing. Individual fusing per capacitor is recommended for fault isolation.
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