W12T 40A Power Relay | PCB Relay for EV Charging, Photovoltaic Systems & New Energy Applications

As renewable energy systems, electric vehicles and energy storage technologies continue to advance, power control systems demand relays with higher switching capability, superior insulation performance and long-term operational reliability. Developed to meet these requirements, the Fanhar W12T 40A Power Relay is specifically designed for electric vehicles, charging piles and photovoltaic (PV) renewable energy systems.

The W12T features a 40A contact switching capability, a maximum dielectric withstand voltage of 4000VAC between coil and contacts, and an optional contact gap of ≥2.1mm. While ensuring high-load switching performance, it also meets the requirements for electrical insulation and safety in new energy equipment.

With a compact PCB-mount design measuring only 31.6 × 27.2 × 18.4 mm, the W12T is available in a wide range of coil voltage options from 5V to 110VDC. The series offers both Standard Type (900mW coil power) and BG Type (1400mW coil power). The relay has obtained UL/cUL, TÜV and CQC certifications, supporting its use in diverse markets worldwide.

40A High-Current Switching Capability for High-Power Equipment

New energy equipment such as EV charging piles and PV inverters require relays with substantial current carrying capacity. The W12T has a rated control load of 40A 250VAC with a maximum switching capacity of 10000VA.

For DC loads, the Standard Type supports 20A 30VDC, while the BG Type supports 20A 48VDC. Additionally, special low contact resistance types are available with NO≤1.2mΩ (32A) and NC≤1.5mΩ (32A). The minimum allowable load is 5VDC 100mA, enabling a wide range of applications from small signal switching to high-power load control.

High Insulation Design for Improved System Safety

Electrical insulation is a critical requirement for renewable energy equipment operating under high-voltage conditions. The W12T offers excellent electrical insulation capabilities:

Maximum dielectric withstand voltage between coil and contacts: 4000VAC

Dielectric withstand voltage between open contacts (BG Type): 2500VAC

Initial insulation resistance: 1000MΩ (at 500VDC)

UL Class F insulation system:Superior insulation performance contributes to improved operational safety and reliability, effectively preventing high-voltage breakdown and leakage risks.

High-Quality AgSnO₂ Contact Material for Extended Service Life

The W12T series uses AgSnO₂ (silver-tin oxide) as the contact material. AgSnO₂ exhibits excellent arc erosion resistance, low and stable contact resistance, good thermal conductivity, and outstanding anti-welding performance. It effectively reduces arcing and extends relay service life, maintaining stable electrical performance even in frequent switching high-load applications.

Reliable Performance in Demanding Industrial Environments

In addition to its electrical performance, the W12T is designed to deliver long-term reliability under demanding operating conditions. The relay operates over a wide ambient temperature range of -40°C to +85°C, making it suitable for renewable energy systems and industrial equipment deployed in diverse climates.

The relay offers a mechanical life of up to 5,000,000 operations and an electrical life of 20,000 operations under 40A 250VAC resistive load, 100,000 operations under 20A 30VDC (Standard Type), and 50,000 operations under 20A 48VDC (BG Type).

Operate time is ≤15ms (Standard) / ≤20ms (BG), and release time is ≤10ms (Standard) / ≤15ms (BG). The relay is also designed to withstand vibration and mechanical shock commonly encountered in industrial applications.

Multiple Coil Voltage Options for Flexible System Design

Different control systems require different coil voltage configurations. To simplify system integration, the W12T is available with multiple DC coil voltage options, including 5V, 6V, 9V, 12V, 18V, 24V, 36V, 48V, 60V, 110V DC.

Standard Type coil rated power is 900mW, while BG Type is 1400mW. The standardized coil design not only improves compatibility with various control circuits but also simplifies product development for manufacturers using multiple voltage platforms.

Compact PCB-Mount Design for Easy Equipment Integration

The W12T features a compact PCB-mount design with outline dimensions of only 31.6 × 27.2 × 18.4 mm and a unit weight of approximately 27g, effectively saving valuable board space. The relay is available in Plastic sealed and Flux proofed types.

In clean environments (free from H₂S, SO₂, NO₂ and dust), the Flux proofed type is recommended. In unclean environments containing these pollutants, the Plastic sealed type is recommended. This design consideration effectively extends the relay's service life in various industrial environments.

Typical Applications

Designed for high-current power switching applications, the W12T is widely used in renewable energy and electric vehicle systems where reliable switching performance and high insulation capability are required:

• Electric vehicles (EV)
• New energy vehicle charging piles
• Photovoltaic (PV) renewable energy equipment

Within these systems, the relay is commonly used for power control, main circuit switching and safety isolation, helping improve system reliability and operational safety.

How to Select Standard Type or BG Type

The W12T is offered in Standard Type and BG Type. The key differences are summarized below:

For general industrial control and standard power switching applications, the Standard Type meets most requirements. For photovoltaic systems, applications requiring larger contact isolation distances, or higher DC voltage scenarios, the BG Type is recommended.