HYET3 Dual Power Auto Changeover Switch – 20A to 1600A,2P/3P/4P

HYET3 Dual Power Automatic Transfer Switch — PC Class, 20A–1600A

The HYET3 Dual Power Automatic Transfer Switch is manufactured by HUYU Electric, leveraging over 30 years of expertise. Designed for AC 50Hz circuits up to 400V, the PC-class ATS is available in seven frame sizes, covering 20A to 1600A. The product offers flexibility with two configuration options: a two-position (I–II) and a three-position (I–0–II) version. The three-position version features a center-off position for dual-break isolation, enhancing safety during maintenance without affecting transfer reliability.

The integrated controller supports an adjustable switching time of 0–255 seconds, allowing customization for generator start-up or grid reconnection delays. With a robust 100kA/120kA limited short-circuit current (Iq) and AC-33i use categories for certain frames, the HYET3 is equipped to handle demanding industrial environments. HUYU Electric provides factory-direct OEM/ODM services with private labeling and complete documentation for auto changeover switches used in backup power and dual-grid applications.

Model Range – Seven Frame Sizes, 20A to 1600A

All HYET3 models are dual power transfer switches built on a unified PC-class platform. Frames up to 630A carry a 100kA Iq rating, while 800A–1600A frames are rated at 120kA. The operation cycle is 30 seconds for smaller frames, extending to 60 seconds for 800A and above for better thermal load management.

Configuration Flexibility & Adjustable Timing

The HYET3 offers two mechanical configurations: two-position (I–II) for standard source-to-source transfers and three-position (I–0–II) with center-off for isolation. Both configurations share the same voltage, current, and pole options, providing full flexibility without altering product families. The switching time is adjustable between 0 and 255 seconds, accommodating diverse generator start sequences and grid reconnection requirements. This makes the HYET3 an ideal choice as an automatic changeover switch for generator applications, where precision timing is often critical.

Technical Specifications

OEM/ODM Supply – Engineered Since 1993

Buyer’s Guide

How to Select a Dual Power Auto Changeover Switch

Key selection criteria for the HYET3 in generator backup and dual-grid systems.

1. Two-Position or Three-Position?

Choose the two-position (I–II) configuration for standard generator automatic transfer switch applications. Select the three-position (I–0–II) version for maintenance procedures or local codes that require visible load isolation. The center-off position is also useful for generator testing without connecting to the building load.

2. Setting the Switching Time

The 0–255S adjustment covers various scenarios. Diesel generators typically need 10–30 seconds to stabilize before accepting load. For dual-grid transfers, a shorter 1–5 second setting minimizes disturbance. This flexibility eliminates the need for external timing relays in most installations.

3. Use Category & Frame Selection

Frames up to 800A default to AC-33B, with AC-33iA available for frequent switching. The 1250A–1600A frames use AC-33iB. Match the use category to the expected operation frequency. For 3-phase systems, choose 3P or 4P based on neutral switching requirements.

4. Short-Circuit Verification

Ensure the HYET3’s Iq rating (100kA or 120kA) exceeds the prospective fault current at the installation point. The PC class rating ensures safe performance in high-fault industrial environments.

Frequently Asked Questions

How does the automatic changeover switch work?

An automatic changeover switch monitors the primary power source and, upon detecting a fault such as undervoltage or phase loss, automatically transfers the load to a standby source — typically a generator. The HYET3 executes this transfer within a user-adjustable time of 0–255 seconds. Once the primary source is restored and stable, the switch returns the load, ensuring seamless power continuity.

What are the common problems with ATS panels?

Frequent issues with ATS panels include contact welding under short circuits and nuisance transfers from incorrect voltage thresholds. The HYET3’s PC class rating certifies short-circuit withstand without welding. Its adjustable switching time and undervoltage settings help eliminate nuisance operations. Regular operational testing and torque checks further prevent field failures.

Is there an automatic transfer switch?

Yes. The HYET3 is a complete automatic transfer switch platform covering 20A to 1600A. It is available in two-position and three-position configurations, with 2P, 3P, and 4P versions for single-phase and 3-phase systems. All units are PC class and include an integrated controller with adjustable timing.

Is it legal to install your own transfer switch?

Installation of an automatic transfer switch must be performed by a licensed electrician in virtually all jurisdictions. This ensures compliance with local wiring codes, proper grounding, and correct integration with the grid. While the HYET3 is designed for straightforward fixed installation, professional installation is required for safety and regulatory compliance.