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 40 A, 480V, 3-pole, NEMA 3R, open transition. Typical loads are a residential service panel, a small retail or office panelboard, a well pump, a sump pump or a light commercial kitchen β circuits where the entire load can be picked up at once and where a compact wall-mounted enclosure is an advantage. The NEMA 3R enclosure is rain-tight and rated for outdoor mounting against a wall or on a pad, so the switch can sit next to an exterior generator without an additional weather shelter. Terminations and footprint. One conductor per pole from #8 AWG to 3/0 AWG on solderless pressure lugs, in an 18 in high by 18 in wide by 8 in deep wall-mount cabinet. At 40 A the withstand rating is 30 kA with an upstream breaker or 200 kA with current-limiting fuses, and the contactor is good for 6,050 mechanical operations. This is the size that goes beside a small residential service to pick up a well pump, a sump pump and a few receptacle circuits β loads where the generator is 10 to 15 kW and nobody wants to think about the switch again. 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 3R cabinet is rain-tight, not watertight: it is built for outdoor mounting against a wall or on a pad, with a hooded or sloped top that sheds water and a gasketed door that keeps driven rain out. What it does not do is keep out dust or hose spray, and the installation still has to do its part β conduit entries need drip loops or sealing hubs so water running down the conduit cannot track into the enclosure, and the mounting surface has to drain. A 3R unit on a north wall in a coastal yard will outlast three indoor units in the same spot, which is why it is the default for anything not under a roof. Matching generator. At 480V with an 0.8 power factor this switch carries approximately 27 kW of load (40 A Γ 480V Γ β3 Γ 0.8 = 27 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.
