Preferred Choice for High-Voltage DC Protection — Dual Breakthroughs in Performance and Reliability of DC Isolation Switch

With the rapid development of new energy, high-voltage DC (HVDC) systems are widely used in photovoltaic (PV), energy storage and rail transit. Their safe operation is critical, as HVDC’s fixed current direction and lack of natural zero-crossing make isolation and fault protection challenging. Efficient, reliable isolation equipment is therefore essential.

As a key HVDC protection device, DC Isolation Switch (DC disconnect switch) physically isolates circuits, cuts off faults, and ensures safety. Unlike AC switches, it is specially designed for hard-to-extinguish DC arcs, and its performance under high voltage directly determines system protection levels.

This article elaborates on the DC Isolation Switch’s performance and reliability breakthroughs, analyzing its core value in HVDC protection to guide application selection.

HVDC scenarios demand high isolation switch performance, including high-voltage tolerance and efficient arc suppression. The DC Isolation Switch achieves dual breakthroughs to meet these needs.

In high-voltage tolerance, the new generation features structural and material upgrades, adapting to 1500VDC and below (and higher for special projects). High-strength insulation and optimized contacts prevent breakdown. According to “Special Standards and Certification Requirements for DC Isolation Switches for Photovoltaic Applications”, IEC 60947-3 compliant switches operate stably at rated voltage, with copper conductor temperature rise ≤60K.

For breaking performance, advanced magnetic blow arc-extinguishing and multi-point breaking quickly suppress DC arcs (which lack natural zero-crossing). For example, ABB Emax series switches achieve 1500V DC / 100kA safe breaking, avoiding faults.

These upgrades break traditional switch limitations, ensuring safe operation of HVDC projects.

Beyond performance, the new DC Isolation Switch improves reliability, solving short service life and high maintenance issues in harsh conditions.

High-wear contacts and optimized transmission extend mechanical life to over 10,000 operations, reducing maintenance and costs—ideal for large PV and energy storage projects.

With IP66 protection, it resists extreme temperatures (-40℃ to 85℃), humidity and salt spray, ensuring stable outdoor/industrial operation.

It also meets IEC 60947-3 and GB/T 14048.3 standards, guaranteeing safety and compliance.

With dual breakthroughs, the DC Isolation Switch is widely used in core HVDC fields: PV plant DC sides (isolation during maintenance), energy storage systems (battery-converter isolation), and rail transit/industrial DC power supplies (fault cutting).

1. “Special Standards and Certification Requirements for DC Isolation Switches for Photovoltaic Applications” — China Electrical Equipment Industry Association

2. IEC 60947-3 Standard: Low-voltage switchgear and controlgear — Part 3

3. ABB Emax Series DC Isolation Switch Product Manual

Q1: What’s the main difference between DC and AC isolation switches? A1: DC switches use special arc-extinguishing (e.g., magnetic blow) for hard-to-extinguish DC arcs; AC switches rely on AC arc zero-crossing.

Q2: What voltage levels can it adapt to? A2: 1500VDC and below; some products support higher levels for special projects.

Q3: How to ensure reliability in harsh environments? A3: IP66 protection, corrosion-resistant materials and optimized structure resist extreme conditions.