(a) General.
(1) Each new sewer pump station shall be provided with an on-site engine generator system including an automatic transfer switch to provide emergency back-up power. The generator shall be rated to continuously provide power for both pumps and all associated equipment simultaneously for the duration of any normal power failure as determined by the city. In no case shall the fuel storage be less than that needed to operate the generating unit for 12 continuous hours.
(2) Each generator system will be evaluated on a case by case basis with adjustments to the requirements as stated herein as deemed appropriate by the city.
(3) Approved manufacturers of the engine generator set are as follows:
a. MTU-On Site Energy.
b. Onan.
c. Catepillar.
d. Olympian.
e. General.
f. Kohler.
(4) Approved manufacturers of the automatic transfer switch are:
a. Russelectric
b. GE/Zenith
c. Asco
d. Lake Shore
e. Standard product of the generator set manufacturer.
(b) Engine.
(1) Engine requirements include the following:
a. Water-cooled inline or V-type, four stroke cycle, compression ignition diesel internal combustion engine.
b. Rating. One hundred percent (100%%) of rated Kw for duration of an emergency outage.
c. Isochronous type governor to maintain engine speed within 0.5%, steady state, and 0.5%, no load to full load, with recovery to steady state within two seconds following sudden load changes. Equip governor with means for manual operation and adjustment.
d. Automatic engine shutdown on high coolant temperature, low oil pressure, overspeed, and engine overcrank. Limits as selected by manufacturer.
e. DC engine starting system with positive engagement, number and voltage of starter motors as required by manufacturer. Include remote starting control circuit, with Run-Off-Auto selector switch on engine I generator control panel.
f. Include a thermal circulation type water heater with integral thermostatic control, sized to maintain engine jacket water at 90 degrees F.
g. Unit mounted radiator using glycol coolant, with blower type fan. Size fan to maintain safe engine temperature in ambient temperature of 110 degrees F with a maximum of 0.5 inches of water static pressure on the fan.
h. Engine Accessories: Fuel filter, lube oil filter, intake air filter, lube oil cooler, fuel transfer pump, fuel priming pump, gear driven water pump, and gear type lube pump. A bypass valve shall be provided to allow lube oil circulation in the event of a failure of the filtering system.
i. Provide vibration isolators between engine/alternator and base frame.
(c) Generator.
(1) Generator requirements include the following:
a. NEMA MG1 three phase, four pole, re-connectable brushless synchronous generator with brushless exciter, 12 lead, 2/3 pitch, random wound, permanent magnet generator.
b. Alternator insulation class. H.
c. Temperature rise. Class F. 130 degrees C rise @ 40 degrees C ambient (Standby duty).
d. Enclosure: NEMA MG1, open drip proof.
e. Include generator-mounted volts per hertz exciter-regulator to match engine and generator characteristics, with voltage regulation plus or minus 1 percent from no load to full load. Include manual controls to adjust voltage droop, voltage level (plus or minus 5 percent) and voltage gain.
f. Frequency regulation: 3 hertz maximum from no load to rated load.
g. Anti-condensation space heater.
h. Diesel engine generator systems shall meet or exceed the emission requirements of the current Environmental Protection Agency regulations for emergency generators.
(2) Accessories.
a. Critical type silencer with muffler companion flanges and flexible stainless steel exhaust fitting, sized in accordance with engine manufacturer's instructions. The silencer shall be mounted within the generator enclosure. The silencer shall be industrial standard construction, all welded, for stationary engine application. The entire exhaust system shall be supported independently of the generator set to prevent transmission of vibration and allow for thermal expansion. Long radius, low restriction fittings shall be used throughout, and pipe size shall be sufficiently large to handle the engine exhaust flow at full load without causing back pressure in excess of that allowed by the engine manufacturer. A stainless steel rain cap shall be provided.
b. Batteries. Heavy duty, diesel starting type lead-acid storage batteries of sufficient capacity to provide a minimum of five full cycle starts for ten seconds crank with ten second rest periods between cranks. Match battery voltage to starting system. Include necessary cables and clamps.
c. Battery tray. Treated for electrolyte resistance, constructed to contain spillage.
d. Battery charger: Current limiting type designed to float at 2.17 volts per cell and equalize at 2.33 volts per cell. Include overload protection, full wave rectifier, DC voltmeter and ammeter, and 120 volts AC fused input. Provide enclosure to meet NEMA 250, Type 1 requirements and NFPA 110 requirements.
e. Line circuit breaker. NEMA AB 1, molded case circuit breaker on generator output with integral thermal and instantaneous magnetic trip in each pole. Unit-mount in enclosure to meet NEMA 250, Type 1 requirements.
f. Control panel. NEMA 250, Type 1 generator mounted control panel enclosure with engine and generator controls and indicators conforming to NFPA 110 Level 2. Panel shall be mounted with vibration isolators. Unit shall include the following devices and features:
1. Panel lighting.
2. Fused DC circuit to protect controls.
3. Three-position run - off - auto selector switch.
4. Frequency meter. 45-65 Hz. range, 3.5-inch dial (or digital display).
5. AC output voltmeter. Three and one-half-inch dial, 2% accuracy, with phase selector switch (or digital display).
6. AC output ammeter. Three and one-half-inch dial, 2% accuracy, with phase selector switch (or digital display).
7. Output voltage adjustment.
8. Provide indicator lights to show the following:
i. Generator off (red).
ii. Generator auto (green).
iii. Generator run (yellow).
iv. Generator warning (yellow).
v. Generator shutdown (red).
9. Provide a scrolling digital display or indicator light to show the following critical data:
i. Overcrank (shutdown).
ii. Low water temperature (shutdown).
iii. High engine temperature.(Shutdown).
iv. Low lube oil pressure (Shutdown).
v. Overspeed (Shutdown).
vi. Low coolant level warning.
10. Audible alarm for any of the above conditions. Provide silence switch; however, activation shall not inhibit any subsequent alarms from sounding.
11. Engine running time meter.
12. Oil pressure gauge.
13. Coolant temperature gauge.
14. Emergency stop switch.
15. Auxiliary relay for indicating that generator set is running or shut down, with contact terminals prewired to terminal strip.
16. Common failure relay. Remotely signals auxiliary fault, emergency stop, high engine temperature, low oil pressure, overcrank and overspeed.
17. Provide terminal strip for remote signaling of alarm and status to SCADA. Coordinate with city as to which conditions are to be monitored.
18. Signal to fuel shut-off solenoid valve on fuel supply line to open when required by the generator.
(3) Weather protective enclosure.
a. Sound attenuated Level 1 reinforced aluminum housing allowing access to control panel and service points, with lockable doors and panels. Sound pressure level shall be limited to 76 dBA at 7 meters. Include fixed louvers, battery rack, battery charger rack, and silencer. Doors shall be equipped with stainless steel locks and hinges. Provide oil and coolant drain extensions. Color shall be manufacturer's standard.
(4) Sub-base fuel tank.
a. Fuel system shall include a double walled, UL approved, welded construction, base mounted fuel tank with integral stub-up area. It shall have the structural integrity to support the engine generator set. The tank must be supplied and warranted by the engine generator set manufacturer and be factory installed. Minimum features shall include:
1. Lockable fuel filler cap. Shall be installed in a five gallon spill containment reservoir with drain and lockable cover.
2. Fuel gauge.
3. Low fuel level alarm.
4. Tank rupture alarm.
5. Fuel line check valve.
6. Fittings for fuel supply, return, fill and vent.
(5) Access platform.
a. If height of fuel tank exceeds 30 inches above top of generator pad, the contractor shall provide an all welded steel structural platform with walkway floor even with bottom of generator skids. Steps shall meet OSHA requirements. A 42-inch wide walkway with aluminum pressure locked grating shall extend all around the generator set. Grating shall be flush top SGF Series by Ohio Gratings Inc., or equal. Bearing bar spacing shall be on 1-3/16 inch centers. Cross bars shall be locked at right angles to, and in the same plane as the top surface of bearing bars. Spacing shall be four inches on center. Grating shall be supported on minimum four-foot centers. Grates shall have an anti-skid surface and shall be designed to support a live load of not less than 200 pounds per square foot with a maximum deflection of 1/180th of the span. A double pipe 42-inch handrail system consisting of 1-1/2 inch diameter aluminum pipe for the rails and vertical posts, and toe plate, shall be provided on the outside perimeter and rails shall be provided on each side of the steps. The platform location shall not interfere with tank fill operations. Color to be selected by owner. Aluminum components shall not be painted. Access platform fabricator shall submit shop drawings with detailed connections and structural calculations sealed by registered North Carolina Structural Engineer.
(6) Duplex receptacle.
a. Provide a GFCI type duplex convenience receptacle inside the weatherproof enclose. Receptacle shall be connected to an external circuit.
(7) Emergency stop switch.
a. Heavy duty, red mushroom push bottom, push-to-stop/pull-to-activate maintained contacts, mounted in NEMA Type 12 enclosure. Provide phenolic label attached to enclosure stating, “GENERATOR EMERGENCY STOP”.
(d) Automatic transfer switch.
(1) Transfer switch requirements include the following:
a. NEMA ICS 10 closed transition automatic transfer switch, service entrance rated with integral overcurrent protection for both sources.
b. Electrically operated, mechanically held transfer switch.
c. Time delay neutral transfer method.
d. Ground fault protection shall be provided on overcurrent protective device.
e. Provide lights mounted in cover of enclosure to indicate normal source available, alternate source available and switch position.
f. Mount test switch in cover of enclosure to simulate failure of normal source.
g. Provide transfer switch auxiliary contacts as follows:
1. One set of relay contacts to open on loss of normal power supply.
2. One set of relay contacts to close when switch in “NORMAL” position.
3. One set of relay contacts to close when switch in “EMERGENCY” position.
4. One set of relay contacts for generator “RUN”.
5. One set of relay contacts for generator “FAIL”.
6. One set of relay contacts interlocked with the pump control panel to open when the switch is in the emergency position to lock out the lag pump.
h. Normal source monitor. Monitor each line of normal source voltage and frequency; initiate transfer when voltage drops below 80% or frequency varies more than 5% from rated nominal value.
i. Thermostatically controlled electric heater sized to prevent condensation under expected weather conditions at the project site. Provide terminals for separate connection of 120 volt power.
(2) Automatic sequence of operation.
a. Initiate time delay to start alternate source engine generator. Upon initiation by normal source monitor.
b. Time delay to start alternate source engine generator. Zero to three seconds, adjustable.
c. Initiate transfer load to alternate source. Upon initiation by normal source monitor and permission by alternate source monitor.
d. Time delay before transfer to alternate power source. Zero to three seconds, adjustable.
e. Initiate retransfer load to normal source. Upon permission by normal source monitor.
f. Time delay before transfer to normal power. Zero to 25 minutes, adjustable; bypass time delay in event of alternate source failure.
g. Time delay before engine shut down. Zero to 25 minutes, adjustable, of unloaded operation.
h. Engine exerciser. Start engine every seven days; run for 30 minutes before shutting down. Bypass exerciser control if normal source fails during exercising period.
i. Alternate system exerciser. Transfer load to alternate source during engine exercising period.
(3) Enclosure.
a. Enclosure. ICS 6, Type 1.
b. Finish. Manufacturer's standard gray enamel.
(Ord. of 11-7-16, No. 10-16)