PC-A400 Automatic Transfer Switch Panel

A 400 A four-pole automatic transfer switch panel with mains sensing, adjustable timers and a manual bypass handle.

Mechanically interlocked so mains and generator contacts cannot close together

Manual bypass handle for transfer during maintenance with the controller isolated

Adjustable start delay, transfer delay, return delay and cool-down run

Volt-free contacts and Modbus for building management system reporting

Specifications

Rated current: 400 A, four pole
Utilisation category: AC-33B, class PC transfer switching equipment
Voltage / frequency: 400 / 230 V, 3-phase, 50 Hz
Enclosure: Floor standing, IP54, form 2 separation
Transfer time: Adjustable, typically 0.5 to 5 s once the set is at voltage
Short circuit withstand: 50 kA rms for 1 s (Icw)
Control: Mains sensing on all three phases, adjustable start and return delays
Dimensions / dry weight: 1000 x 800 x 2000 mm / 210 kg

Product detail

The transfer switch is the part of a standby installation that is specified last and blamed first. Its rating has to match the incoming supply, not the generator, because it carries the full building load whenever the mains is healthy, which is almost all of the time.

Sizing

Rated current is selected against the incoming protective device, and the short circuit withstand against the prospective fault level at the point of installation. A switch rated for the set rather than for the mains is the single most common error we see on a drawing issued for tender.

Timers

Four delays matter and all four are adjustable: the start delay that stops a momentary dip starting the set, the transfer delay that lets the set reach stable voltage and frequency, the return delay that stops the load bouncing back onto an unstable mains, and the cool-down run that lets the turbocharger unload before the set stops. Values are set at commissioning against the load, not left at factory defaults.

Neutral switching

Supplied four pole as standard, which switches the neutral and keeps the two supplies separately earthed. Three-pole variants are available where the earthing arrangement calls for it. [Client to confirm the earthing arrangement and the protection discrimination study for the installation.]

Bypass

A manual handle allows transfer with the controller isolated, so the switch can be exercised or maintained without dropping the load.