A 3 phase changeover switch transfers a three-phase load between two power sources, such as the main supply and a compatible generator or solar inverter. In a break-before-make arrangement, it disconnects one source before connecting the other, preventing the two sources from being connected together through the switch.

The operator selects the supply using three positions:

• Position 1: connects the load to the first power source.
• Position 0: disconnects the switched load conductors from both sources.
• Position 2: connects the load to the alternative source.

The operator moves the switch through the off position to change supplies.

• Manual changeover switches require an operator to select the power source and suit applications where manual intervention is acceptable.
• Automatic transfer switches (ATS) use a controller to monitor supply conditions and initiate transfer when the configured conditions are met.

Automatic operation does not guarantee an uninterrupted supply. Open-transition switching interrupts the load, and generator startup or programmed delays can extend the outage.

• 2P: suits appropriate two-conductor circuits, including some single-phase arrangements. It cannot switch all three phase conductors.
• 3P: switches the three phase conductors.
• 4P: can also switch the neutral conductor.

The choice depends on the earthing arrangement, source configuration and applicable wiring requirements; neutral switching is not required in every three-phase installation.

Typical applications include:

• Industrial and commercial facilities: alternative-source selection for pumps, compressors, HVAC and designated distribution circuits.
• Renewable energy and residential systems: selection between compatible AC supplies from the grid, a generator or an inverter where a three-phase installation is available.
• Farms: backup supply selection for suitable refrigeration or pumping circuits.
• EV charging facilities: selecting between supplies where the charging equipment, backup capacity and electrical design support that arrangement.
• Construction sites: utility or generator selection through appropriately rated equipment housed for site conditions.

These are application examples. The switch, backup source and any inverter must match the circuit ratings, load characteristics and intended operating arrangement.

Select the switch using the circuit's design current, operating voltage, frequency, load type and the manufacturer's utilization-category ratings. Consider motor starting current, ambient temperature and coordination with the circuit's protective devices. A building or appliance type alone does not determine the required amperage.

• DIN-rail changeover: the YCBZ-40 Changeover Switch lists 240/415 V AC, 50/60 Hz, 16/25/32/40 A, 1P/2P/3P/4P, a 1-0-2 contact form and 35 mm DIN-rail mounting. It operates as a switch-disconnector and lists IEC 60947-3.
• Rotary control: LW26 and LW28 universal changeover switches offer arrangements for manual circuit control, motor control and measurement. Select the contact sequence and rating for the intended function.

A power-source changeover switch and a rotary control selector can serve different functions. Check the exact model's wiring diagram, mounting space, terminals, conductor sizes, service life and documented standards before ordering.

A switch-disconnector does not by itself provide overload, short-circuit, surge or arc-fault protection. Coordinate it with suitable circuit breakers, fuses and other protective devices required by the installation, including its short-circuit requirements.

Outdoor use depends on the complete installation's enclosure rating and environmental limits. CNC YCBZ-40 is listed as IP20, which does not provide protection against rain. Use an appropriately rated enclosure and check temperature, moisture, dust and cable-entry requirements; do not treat a bare DIN-rail switch as weatherproof.

Price depends on manual or automatic operation, current rating, pole configuration, enclosure, accessories and order quantity. Compare quotations for the same configuration and duty.

For a CNC quotation, provide the operating voltage, required current, pole configuration, power-source types, quantity and delivery destination. Share your load details and source arrangement with CNC Electric's technical team for help identifying suitable product options.