Product Overview
The GE Zenith ZTX series is a compact automatic transfer switch built on a double-throw, mechanically interlocked contactor mechanism: electrically operated and mechanically held, with no solenoid trip to wear out and no neutral position to mis-sequence. The platform covers 30 A to 1,200 A at 200-480 Vac and is listed to UL 1008, CSA and IEC. Zenith Controls was a General Electric business; the ZTX range is now manufactured by ABB and the catalog numbers are unchanged, so a ZTX ordered today is the same switch that has been installed in North American light-commercial buildings for decades. This unit is rated 200 A, 480V, 3-pole, NEMA 1, open transition. Typical loads are a whole-building distribution panel, a rooftop packaged unit group, a small data or telecom room, a clinic or a restaurant β installations where the transfer switch is sized to the full service and must coordinate with the upstream overcurrent protection. The NEMA 1 enclosure is intended for indoor installation in a dry, protected space such as a mechanical room or an electrical closet. Terminations and footprint. The lug range steps up here to one conductor per pole from #6 AWG to 250 kcmil, in the same 24 in by 18 in by 10 in cabinet. 250 kcmil is the practical limit of what a single lug in a box this size takes comfortably, and it is also where feeders start arriving in conduit that has to be planned for at rough-in. This is the top of the group that still mounts on a wall. Service arrangement. This is a 480Y/277 V three-phase four-wire switch, the standard industrial and large-commercial service in North America: 480 V for motors, chillers and process equipment, 277 V for lighting, with the neutral bonded at the service and carried solid through the transfer switch. This is the voltage at which arc-flash energy climbs fastest, so the upstream coordination study matters more here than at 208 V. Enclosure. The Type 1 cabinet is for indoor use in a dry, protected space β a mechanical room, an electrical closet, a plant room β where the only thing it has to keep out is incidental dust and the occasional touch. It is not rain-tight and not watertight: mounting one on an exterior wall, even under a soffit, invites water in through the door seam and the conduit knockouts, and the first sign is usually a rusted mechanism rather than a tripped breaker. If the switch has to live outdoors, the 3R version of the same rating is the one to order. Matching generator. At 480V with an 0.8 power factor this switch carries approximately 133 kW of load (200 A Γ 480V Γ β3 Γ 0.8 = 133 kW, three-phase). Size the standby generator so that its standby rating meets or exceeds that figure, and confirm the generator's two-wire automatic-start contacts are compatible with the transfer switch controller. Control. The ZTX is supplied with the MX60 microprocessor control panel: undervoltage sensing on Source 1 at 90 % pickup and 80 % dropout, voltage and frequency sensing on Source 2 at 90 % voltage and 95 % frequency pickup, and fixed time delays β engine start 3 s, transfer to generator 15 s, retransfer to utility 5 minutes, engine cool-down 1 minute. The panel carries LEDs for source availability and switch position, pushbuttons for test, exerciser set, timer bypass and program cancel, and a selectable 7 / 14 / 21 / 28-day generator exerciser (factory set to 28 days). All time delays are fixed and not field-adjustable β that is deliberate: the ZTX is aimed at installations where nobody is going to re-commission the switch after the building is handed over. Three-pole switching. The three phase conductors are switched with the neutral solid, the standard arrangement for 208Y/120 V and 480Y/277 V three-phase services where the neutral is bonded at the service and must not be opened. Supply. Supplied as a genuine GE Zenith Controls (now ABB) ZTX unit, brand new and factory original, packed for export from our Dongguan warehouse. Ask us for the outline drawing, wiring diagram and MX60 control manual for this exact catalog number.
