SEAL-O-RING 5P0840 - Caterpillar

A typical transfer switch (200 to 400 amp) is shown above. Components are housed inside a standard NEMA 1 enclosure for switches rated 400 amps and below. A NEMA 1 enclosure is a general purpose enclosure for use in clean, dry environments (the enclosure does not have door gaskets).For switches rated more than 400 amps, a NEMA 12 enclosure is provided as standard. NEMA 12 enclosures are non-ventilated, dust-tight and drip-tight. Type 12 enclosures are intended for use indoors to protect the enclosed equipment against fibers, filings, lint, dust, dirt, light splashing, seepage, and external condensation of non-corrosive liquids.In order to maintain the NEMA 12 enclosure, no holes through the enclosure, no conduit knockouts or conduit openings are permitted. Oil-tight or dust-tight mechanisms may be mounted through holes in the enclosure when provided with oil resistant gaskets. Enclosure doors have been factory equipped with oil resistant gaskets. Some transfer switches may have an optional NEMA 3R enclosure. See "Transfer Switch Options" in this manual.Transfer Switch Major Components (Typical 200 To 400 amp)
Switch Position-Normal Indicator Light (1) - Clear light comes on to indicate that load circuits are connected to the normal power source side. Also see transformer T2 (10) and auxiliary contacts on transfer mechanism (15). Switch Position-Standby Indicator Light (2) - Red light comes on to indicate that load circuits are connected to the standby power source side. Also see transformer T2 (10) and auxiliary contacts on transfer mechanism (15). Standby Operating Indicator Light (3) - Amber light comes on to indicate the standby generator has started and is running. Also see transformer T1 (11). Operating Mode Switch SW2 (4) - Use this 3-position switch to select normal automatic operation or any of two different test modes, as follows:1. Automatic Mode - Set switch to this position for normal automatic operation. With AUTOMATIC MODE selected, the system will monitor normal source voltage. Any drop in that source voltage below a pre-set value and for a pre-set time interval will result in an automatic standby generator startup signal and transfer of load circuits to the standby power source, when conditions are correct.2. Normal Test Mode - Setting the switch to NORMAL TEST position will simulate a loss of normal source voltage, and will result in an automatic standby generator startup signal and transfer to the standby power source, just as though an actual normal source failure has occurred. When the switch is reset back to the AUTOMATIC MODE, re-transfer to the normal source and standby generator signal shutdown will occur as pre-set by system