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Automatic Transfer Switch
The fire pump automatic transfer switch shall be electrically operated - mechanically held on both the emergency and normal power
source sides, and rated for continuous duty in an unventilated enclosure. The transfer switch shall be rated and listed for fire pump
service and be UL 1008 listed and FM Approved, and shall be electronically controlled for automatic switching, and capable of manual
operation.
The transfer switch logic shall monitor the emergency power source for all three phases before permitting transfer from the normal
source. Transfer switches monitoring only two phases of either source are not acceptable. The fire pump automatic load transfer switch
specified shall include the following features:
• Full Phase Protection – the solid state phase monitor shall be a field adjustable, close differential type, with 85-100% pickup and 75-
98% dropout. A single adjustment shall set all phases.
• Solid state, three phase voltage and frequency monitor on generator output to prevent transfer prior to proper output parameters,
adjustable 85-100% of generator voltage and frequency, with adjustable dropout of 75-85% setting.
• Adjustable 2 to 30 minutes on retransfer of load to normal.
• Adjustable 2 to 30 minutes cool-down timer when the generator set runs unloaded after retransfer to line.
• Motor load decay time delay, adjustable from 1.5 to 15 seconds and operating on transfer to either source.
• Adjustable 0.5 seconds to 5 minutes time delay on transfer to emergency source after verification of emergency source voltage and
frequency.
• Test switch to simulate normal power failure.
• Phase loss and phase reversal monitor to initiate transfer to emergency power.
• “Normal” and “Emergency” position LED’s.
• Engine start contacts for generator.
• Aux. contacts for normal and emergency positions.
• Emergency source isolating switch/motor circuit protector, as a means of disconnect. The switch shall include aux. contacts to inhibit
engine starting when switch is open.
• Audible and visual alarm to indicate isolating switch is open, with “Normal-Silence” selector switch and re-ring function.
• Push button to bypass retransfer to normal time delay.
The following diagnostic LED indications shall be provided:
Normal Source Voltage O.K. Green LED
Emergency Source Voltage O.K. Red LED
Emergency Frequency O.K. Green LED
Transfer to Emergency Timing Red LED
Transfer to Normal Timing Red LED
Engine Running Unloaded Timing Red LED
The transfer switch shall be model LX450 as manufactured by Hubbell Industrial Controls.