STS is a piece of switchgear that gets compared on price — until a real-world transfer event happens. Here’s where transfer speed and field serviceability actually matter.
Most data center IT loads tolerate 10-20 ms outages. A 30 ms transfer trips servers, dumps in-flight transactions, and triggers SLA penalties. Sub-20 ms transfer keeps the load running.
Mechanical STS rely on contactors that wear with every transfer. After 10,000 cycles they slow down or fail. Solid-state STS transfers electronically — no mechanical wear, predictable life.
Many high-power STS require rear-side service — meaning panel rooms need rear clearance, and maintenance happens during full system shutdown. Front-side service halves the downtime window.
Voltage sags, frequency excursions, and harmonic events shouldn’t all trigger transfer. Programmable thresholds let you set transfer criteria per site — so the STS only acts when it should.
Four properties built into every ESTS module — from the 250 kW to the 1000 kW unit.
Solid-state thyristor-based transfer with full-cycle voltage detection. Transfer completes in under 20 ms — within the ITIC curve for sensitive IT loads. Half the response of mechanical-contactor STS.
Solid-state design eliminates the mechanical losses and contact resistance of contactor-based switching. Stable efficiency across the full load range.
All control boards, modules, and connections accessible from the front. No rear clearance required in panel rooms. Hot-swap-capable power modules on 500 kW and 1000 kW SKUs.
Voltage, frequency, and phase-angle thresholds all configurable per site. Modbus TCP/RS485/CAN communication for integration with EMS or SCADA. Optional RJ45 parallel for redundant configurations (500 kW / 1000 kW).
For full technical parameters across communication, control, environment, and certifications, download the complete datasheet below.
From procurement shortlists to commissioning — the ten questions we hear most often during technical due diligence.
Specified at < 20 ms. Typical measurements during commissioning are 16-18 ms. The transfer is deterministic — there’s no random jitter. Detection and switching are both electronic, no mechanical contactors involved.
This puts the unit within the ITIC (formerly CBEMA) curve for IT load tolerance, meaning sensitive computing equipment will not see the transfer as an outage event.
For installations above 12 units, we recommend our EMS as an upper-level coordinator for SOC balancing and energy optimization, not for real-time control. Real-time grid support remains VSG-based.
The product is designed based on a 4-unit parallel architecture. Standard delivery primarily consists of single-unit operation. We also support a 2-unit parallel solution, which is fully commissioned at the factory prior to shipment. For larger-scale projects, we can evaluate and customize up to a 4-unit parallel system (maximum single-system capacity of 4 MW); please note that on-site commissioning and sign-off by our authorized engineers are mandatory for this configuration. Furthermore, to meet higher capacity or ultra-fast transfer requirements, we can provide matching Fast Transfer Switches up to 4000A.
Voltage thresholds (over/under, configurable percent and time delay), frequency thresholds (Hz deviation and time delay), and phase-angle deviation. All configurable via Modbus or the local HMI. Typical default: ±10% voltage, ±2 Hz, transfer if violated for > 20 ms.
Programmable inhibit conditions also supported — e.g., do not transfer during scheduled maintenance windows, or do not transfer if the alternate source is also out of spec.
Recommended annual visual inspection and torque check on power connections. The solid-state switching elements have no defined wear life — there are no mechanical contactors that need replacement.
Module replacement (in 500 kW / 1000 kW units) is hot-swappable with proper procedure. The control boards are field-replaceable in under 30 minutes.
The ESTS series is designed to integrate with our 105/125 kW grid-forming PCS modules — the STS handles the source-side switching while the PCS handles inverter operation. The combined system supports VSG control and seamless mode transitions.
For third-party PCS integration, contact engineering with the PCS communication protocol (Modbus TCP, CAN, or proprietary). Our application engineers can confirm compatibility within 48 hours.
The ESTS series is IP20, designed for installation inside switchroom or panel-room enclosures. For outdoor deployment, the unit needs to be installed inside an IP54 or higher outdoor cabinet with thermal management.
If outdoor cabinet integration is part of your project, our engineering team can specify the required cabinet thermal load (cooling/heating) based on the STS rating and ambient envelope.
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