4P Automatic Transfer Switch | Dual Power Supply ATS WCQ2C

It is the four-pole version of Westhomes' WCQ2C automatic transfer switch, designed to switch all three phases and the neutral between two three-phase AC sources — typically utility mains and a standby generator. Switching the neutral together with the phases is required when the standby source is a separately derived generator with its own neutral-to-earth bond.

If the neutral is not switched, the mains neutral and the generator neutral can become paralleled during a transfer, creating parallel earth paths, circulating currents, and unwanted neutral currents that can damage equipment and confuse residual-current protection. A 4P ATS isolates the neutral on the dead source, so only one neutral-to-earth bond is active at any time.

It is used for standby generator backup in commercial buildings, factories, clinics, office towers, hotels, and small data closets where the generator has its own N-E bond. It is also used where two independent utility supplies must be fully isolated on all four conductors, or where local wiring rules mandate a 4-pole ATS for emergency supplies.

The WCQ2C 4P is offered in compact frame sizes covering ratings commonly from 16A up to 100A (with larger frames in sister series for higher currents). Size the switch to the maximum load current plus margin, and remember that motor and transformer inrush must be checked against the switch's use category (e.g., AC-33).

The controller continuously samples voltage, frequency, and phase sequence on both sources. On a mains fault it waits out the set delay, starts the generator, waits for the generator output to stabilise, then breaks all four poles from the mains and makes them to the generator. When mains returns and stays within tolerance for the re-transfer delay, it transfers back and stops the generator after a cool-down period.

Contact transfer time is typically sub-100 ms to a few hundred milliseconds on this class of open-transition ATS. The actual load interruption is longer because the switch waits for the generator to start and reach rated voltage and frequency — usually 5–15 seconds. Delays are adjustable to ignore brief utility flicker.

Mount the ATS adjacent to the distribution board, run L1/L2/L3/N from both sources to the inputs and the same four conductors to the load output, and keep the load-side neutral isolated from earth (do not re-bond it). Run the generator control cable in separate conduit, verify phase rotation, earth the enclosure, and perform a full load-transfer test before putting the installation into service.

Yes. It runs automatically in normal service but offers local pushbutton selection, a manual operating handle, and auxiliary contacts for remote status and alarm indication (source 1 active, source 2 active, common fault, generator run command). This makes it suitable for BMS/SCADA integration and periodic remote testing.

The WCQ2C 4P is designed and type-tested to IEC 60947-6-1, the IEC standard for low-voltage transfer switching equipment up to 1000 V AC, which defines ratings, impulse withstand, short-time current, and switching duty. It is normally CE-marked, and type-test reports are available for tender and certification use.

A manual 4P changeover is a purely mechanical, lever-operated interlock with no sensing or control electronics — an operator must make every transfer and start the generator by hand. The WCQ2C 4P is an integrated automatic system that monitors both sources, sequences the generator, and switches all four poles safely and repeatably without any person on site. It is the correct choice for critical, unattended, or code-required emergency power systems.