Table of Contents

DC SPD Manufacturer

High-reliability DC surge protective devices for PV, ESS, EV charging, telecom, and industrial DC systems

DC surge protective devices (DC SPDs)—also called DC surge protectors or DC surge arresters—limit lightning-induced and switching surges on direct-current circuits by clamping the over-voltage to a safe voltage protection level (Up). Typical deployments include PV strings and combiner boxes, inverter DC inputs, battery energy storage (ESS) DC busbars, EV fast-charging cabinets, telecom base stations, and industrial DC controls. SPDs work alongside DC circuit breakers and DC fuses to create a complete protection scheme up to 1500 VDC.

DC circuit breakers: /dc-circuit-breaker-manufacturer/
DC fuses: /dc-fuse-manufacturer/

What a DC SPD does (in plain terms)

Clamps surges: turns a dangerous spike into a short-duration, limited peak (Up).
Protects equipment: MPPT inputs, batteries, contactors, PLCs, and DC/DC converters.
Fails safely: thermal links disconnect aged MOVs under temporary over-voltage (TOV), with a visual indicator and remote alarm contact for maintenance.

Key ratings on a datasheet

Uc (continuous operating voltage) — the DC voltage the SPD withstands continuously.
In (nominal discharge current) — durability test current (8/20 μs).
Imax (maximum discharge current) — one-shot capability (8/20 μs).
Iimp (10/350 μs) — lightning current rating for Type 1 SPDs.
Up — residual voltage after clamping; lower is better if energy handling is still adequate.

Product portfolio (PV & ESS focused)

PV DC Type 1, Type 2, and Type 1+2 (600 / 1000 / 1500 VDC)
Pluggable cartridges, polarity-marked bases, visual status windows, and remote alarm contacts.
ESS / battery DC SPDs
Higher In/Imax, low Up, robust SCCR / back-up fuse coordination for battery fault energy.
String/combiner SPDs (DIN-rail)
Protection modes: +/– to PE (common-mode) and + to – (differential-mode).
Accessories
Finger-safe bases, in-line options for string level, spare modules, and wiring labels.
Combiner-level protection integrates with our DC distribution box and DC isolator switch ranges

How a modern DC SPD is built

MOV stacks provide fast clamping and energy absorption.
GDT tubes add high surge robustness and improved TOV behavior in MOV+GDT hybrids.
Thermal disconnect isolates end-of-life modules and drives the flag indicator.
Remote signaling: dry contact (form C, NO/NC) mirrors the flag for SCADA/PLC.
Pluggable design: quick module replacement without rewiring the base.

Selection guide (with PV/ESS examples)

Define the system: max DC voltage, topology (floating or negative-grounded), location (array/combiner, inverter DC input, ESS rack).
Choose the SPD type
- Type 1 (10/350 μs): at LPZ boundaries exposed to direct lightning currents (e.g., service entrance of large PV plants with external LPS).
- Type 2 (8/20 μs): for induced/switching surges inside buildings—PV combiner boxes, inverter DC inputs, ESS racks.
- Type 1+2: combined performance when in doubt or at exposed sites.
Pick Uc with margin
- Rule of thumb: Uc ≥ 1.2× the highest operating DC voltage.
- PV example — 1500 VDC array: if Voc(max) ≈ 1500 V, choose Uc 1500 VDC modules specifically rated for PV.
- ESS example — 800 VDC battery bus: Uc 1000 VDC hybrid SPD often fits, depending on BMS/TOV conditions.
Size the energy ratings
- String/combiner SPD: typical In 20–40 kA (8/20 μs), Imax 40–80 kA; select Up ≤ 2.5–3.0 kV for 1000–1500 V arrays.
- ESS bus SPD: choose higher In/Imax and verify SCCR with back-up Verify SCCR with back-up fusing—see DC fuses—or upstream MCCB—see DC circuit breakers
Select protection mode
- +/– → PE (common-mode) for lightning-related surges and insulation stress.
- + → – (differential-mode) to protect electronics; many PV systems use both modes.
Coordinate protection
- Follow datasheet back-up fuse guidance (e.g., gPV or aR links) to achieve the declared short-circuit withstand.
- For multi-stage protection (Type 1 at service, Type 2 at inverter), respect separation distances or use decoupling inductance if required.

Lead length really matters
Keep each SPD lead as short and straight as possible (ideally < 0.5 m per lead). Use a “V” or “Y” connection directly to the protected terminals and a low-impedance PE bar. Shorter leads = lower effective Up at the equipment.

Installation best practices

Mount on DIN rail inside a rated enclosure (IP20 bases; IP65+ for outdoor combiner boxes).
Observe polarity and wiring diagrams; many DC SPDs are polarized.
Bond array frames, racks, and PE well; poor bonding defeats SPD performance.
Use proper conductor cross-section (e.g., 10–35 mm² Cu) and torques; avoid loops and tight bends.
Place SPDs at both ends of long cable runs (array and inverter).
For floating vs negative-grounded PV arrays, use the mode recommended by the inverter/PV datasheet.

Testing & compliance

IEC 61643-31 (DC/PV SPD): IEC Webstore — https://webstore.iec.ch/searchform?q=61643-31
IEC 61643-11 (AC SPD): IEC Webstore — https://webstore.iec.ch/searchform?q=61643-11
UL 1449 (North America): UL resource — https://www.ul.com/resources/ul-1449-standard-surge-protective-devices
RoHS/REACH materials compliance and lot traceability (QR code on label).

(External links above are DoFollow references to standards bodies.)

Quality & manufacturing you can audit

Controlled MOV/GDT sourcing, moisture-managed storage, and pre-aging.
Optical/X-ray inspection of assemblies; thermal-link calibration and contact verification.
100% routine tests: insulation, indicator function, remote alarm contact, and module fit.
DFMEA/PFMEA, SPC on critical parameters, full serialization for field traceability.

Applications (long-tail examples)

1500 V DC SPD for utility-scale solar farms (string and central inverters)
PV combiner box surge protector with pluggable cartridges and remote alarm
Battery energy storage DC surge protection with high SCCR coordination
EV DC charger surge protection (cabinet DC bus, OBC auxiliary DC)
Telecom –48 V DC plant SPD (low Up)
Industrial DC drives/rectifiers and railway DC auxiliaries

Why work with a custom DC SPD manufacturer

Exact Uc / type / In / Imax / Up matched to your topology and risk level
MOV-GDT hybrid designs for tougher TOV scenarios and longer life
Remote signaling (NO/NC) options for plant monitoring
Clear back-up fuse and SCCR coordination notes for approval
Fast delivery, OEM branding, and spare-cartridge programs

Request a custom quote

Send your system VDC, SPD type (1 / 2 / 1+2), Uc, target In/Imax/Up, protection mode (±→PE or +→–), enclosure rating, cable lengths, and whether you need remote alarm contacts. We will recommend models, share coordination charts, and confirm lead time.

FAQ

Q1. Type 1 vs Type 2 vs Type 1+2—how do I choose?

Type 1 handles 10/350 μs lightning currents at LPZ boundaries. Type 2 handles 8/20 μs surges within installations. Type 1+2 combines both. Large PV plants often use Type 1 at service entrance and Type 2 at inverter inputs.

Q2.How do I pick Uc for a 1500 V PV array?

Base it on Voc(max) with margin; many plants use Uc 1500 VDC modules explicitly listed for PV. Never underspec Uc or the SPD may age prematurely.

Q3. What is TOV and why does it matter?

Temporary over-voltage (TOV) occurs during ground faults or abnormal conditions. Hybrid MOV+GDT SPDs tolerate TOV better and disconnect safely via thermal links.

Q4.Type 1 vs Type 2 vs Type 1+2—how do I choose?

Yes in many PV systems. ±→PE (common-mode) addresses lightning coupling; +→– (differential) protects electronics. Many DIN-rail bases accept three cartridges to cover both.

Q5.Which back-up fuse should I use?

Follow the SPD datasheet (e.g., gPV for PV strings or aR semiconductor fuses for ESS). For fuse selection basics, see /dc-fuse-manufacturer/.

Q6.Can I use an MC4 in-line SPD instead of a DIN-rail SPD?

In-line SPDs are convenient at string level, but combiner and inverter inputs typically use DIN-rail pluggable units with higher energy and easier maintenance.

Q7. Are DC SPDs polarized?

Most are. Respect “+” and “–” markings and wiring diagrams; mis-polarity can disable protection.

Q8. Will an SPD affect MPPT efficiency?

No—properly selected SPDs have negligible leakage and are installed in parallel, not in series with the DC current path.

Q9. Can I mount SPDs outdoors?

Yes, in a suitable IP-rated enclosure (e.g., IP65 combiner box) within the SPD’s temperature range.

Q10. How often should I replace modules?

Check the status window during inspections and tie the remote contact to alarms. Replace any cartridge that shows “tripped” or after major surge events according to site policy.

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