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20kA Compact AC Surge Protective Device for Distribution Boards

This compact AC surge-protective device is designed for sub-distribution boards, machinery panels, and control cabinets where DIN-rail space is limited.

Each protection path provides a nominal discharge current of 10 kA and a maximum discharge current of 20 kA under an 8/20 μs waveform. The slim 18mm modular design is available in single-phase and three-phase configurations, with Uc options from 275V to 440V AC.

The pluggable design includes an internal thermal disconnector, green/red status indication and optional remote signalling for panel monitoring and maintenance.

Product: Compact AC Surge Protective Device
Internal Model: LDSP1s-D20
Application: Sub-distribution boards and control cabinets
SPD Classification: Type 2+3*
Rated Voltage, Un: 230V AC
Uc Options: 275V / 320V / 385V / 440V AC
In: 10kA, 8/20μs
Imax: 20kA, 8/20μs per protection path
Uoc: 6kV
Up: ≤1.2kV to ≤1.6kV, depending on model
Module Width: 18mm per protection path
Configurations: 1+0 / 2+0 / 3+0 / 4+0 / 1+1 / 3+1
Maximum Backup Fuse: 32A gG
Mounting: 35mm DIN rail
Status Indication: Green / Red
Remote Signalling: Optional
Protection Degree: IP20

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Product Description

Product Overview

This compact AC SPD is intended for low-voltage panels where installation space matters just as much as surge performance.

At only 18mm wide per protection path, it can be configured for single-phase and three-phase systems without occupying the same DIN-rail space as many higher-capacity SPD series.

The product provides In 10kA and Imax 20kA per protection path. It is intended to limit transient overvoltages associated with indirect lightning effects and switching events in sub-distribution boards, machinery panels and industrial control cabinets.

Uc options of 275V, 320V, 385V and 440V AC allow the SPD to be matched to different system voltages and protection requirements. The corresponding voltage protection level ranges from ≤1.2kV to ≤1.6kV.

Key Features

Compact 18mm DIN-Rail Design
In 10kA and Imax 20kA per Protection Path
Low Voltage Protection Level
Single-Phase and Three-Phase Configurations
Pluggable Module and Thermal Disconnection
Visual and Remote Status Monitoring

Technical Specifications

Parameter	Specification
Public Product Name	Compact Type 2+3 AC Surge Protective Device
Internal Model Series	LDSP1s-D20
SPD Classification	Type 2+3 / Class II+III*
Protection Technology	Metal Oxide Varistor, MOV
Product Structure	Pluggable protection modules
Rated Operating Voltage, Un	230V AC
Maximum Continuous Operating Voltage, Uc	275 / 320 / 385 / 440V AC
Nominal Discharge Current, In	10kA, 8/20μs
Maximum Discharge Current, Imax	20kA, 8/20μs per protection path
Open-Circuit Voltage, Uoc	6kV
Voltage Protection Level, Up	≤1.2kV to ≤1.6kV
Short-Circuit Current Rating, Isccr	25kA
Response Time	≤25ns
Maximum Backup Fuse	32A gG
Thermal Disconnector	Integrated
Main Terminal Capacity	2.5–25mm²
Remote Signalling	Optional
Remote Contact Rating	250V AC / 0.5A; 30V DC / 3A
Maximum Remote-Signal Wire Size	1.5mm²
Installation	35mm DIN rail
Module Width	18mm
Dimensions per Module	Approx. 90.5 × 18 × 66.5mm
Status Indication	Green / Red
Operating Temperature	−40°C to +85°C
Degree of Protection	IP20
Enclosure Material	Thermoplastic; supplied document states UL94-V0
Referenced Standards	IEC 61643-11, EN 61643-11, GB/T 18802.11

Voltage Options

Version	Un	Uc	TOV, 5s	TOV, 120min	In	Imax	Uoc	Up
275V Version	230V AC	275V AC	335V AC	440V AC	10kA	20kA	6kV	≤1.2kV
320V Version	230V AC	320V AC	335V AC	440V AC	10kA	20kA	6kV	≤1.3kV
385V Version	230V AC	385V AC	500V AC	650V AC	10kA	20kA	6kV	≤1.5kV
440V Version	230V AC	440V AC	580V AC	770V AC	10kA	20kA	6kV	≤1.6kV

Choose the Uc rating from the maximum continuous voltage that may appear across the SPD terminals in the actual electrical system.

A higher Uc value is not automatically better. The correct model must remain stable under normal and temporary overvoltage conditions while providing an Up value suitable for the equipment being protected.

The 1+1 and 3+1 configurations use a dedicated 255V AC N-PE module.

Low Up Protection for Control and Automation Equipment

The series provides a voltage protection level from Up ≤1.2kV to ≤1.6kV, depending on the selected Uc version.

This makes it suitable for coordinated downstream protection in panels supplying PLCs, power-supply units, automation controllers, building-control equipment and other electronic loads that may be sensitive to transient overvoltage.

The product should be used as part of a coordinated surge protection system. Where the installation is exposed to direct lightning current, an upstream Type 1 or Type 1+2 SPD may also be required.

Typical Applications

The compact 20kA AC SPD is designed for downstream electrical panels where DIN-rail space and low residual voltage are key selection factors.

Typical applications include:

• Commercial sub-distribution boards

• Machinery and automation control panels

• PLC and industrial control cabinets

• Building-management system panels

• Power-supply and electronic control cabinets

• Compact electrical panels supplying sensitive equipment

OEM Compact AC Surge Protectors for Panel Builders

Yueqing Nantai supports electrical distributors, panel builders, automation suppliers and private-label electrical brands with OEM production for compact AC surge protective devices.

Available options may include brand printing, model labels, packaging, barcodes, manuals, remote-signalling versions and supporting technical documents.

UC ratings, protection configurations and electrical parameters must remain consistent with the validated product platform and applicable compliance documents. Any requested technical change

is subject to engineering and compliance review.