B37 ATS Specs.pdf

109016

AUTOMATIC TRANSFER SWITCHES 16621-1

SECTION 16621 - AUTOMATIC TRANSFER SWITCHES

PART 1 - GENERAL

1.1 DESCRIPTION:

A. This section includes the furnishing, installation, and connection of automatic transfer switches.

1.2 APPROVED MANUFACTURERS:

A. Russell Electric, ASCO, Zenith, Onan, Cummins, Kohler and Caterpillar. If ASCO transfer switches are provided, contractor shall provide electrical room layout showing adequate space for all equipment due to the larger size of ASCO transfer switches.

NOTE: Pad and conuit entry locations are based on ASCO. If a different manufacturer is used, the existing conduits and pads shall be used.

PART 2 - PRODUCTS

2.1 AUTOMATIC TRANSFER SWITCHES, GENERAL:

A. Automatic transfer switches shall be in accordance with UL, NEMA, NEC, ANSI, as specified and as shown on the drawings.

B. Automatic transfer switches are to be electrically operated, mechanically held, open contact type, without integral overcurrent protection. Transfer switches utilizing automatic or non-automatic molded case circuit breakers as switching mechanisms are not acceptable.

C. Automatic transfer switches shall be UL listed under UL 1008 and, where applicable, also meet the additional withstand test requirements as specified.

D. The unit shall be completely assembled and factory wired so that only external circuit connections are required in the field. The unit shall include, but not be limited to, operating mechanism, main contact, auxiliary contacts, timers, pilot lights, switches, and auxiliary sensing devices.

2.2 RATINGS, MARKINGS AND TESTS:

A. Ratings:

1. Phase, voltage and ampere rating shall be as shown on the drawings.

Switches shall be break before make switched neutral 4 pole for 3 phase 4 wire systems. The ampere rating shall be for 100 percent continuous load current.

AUTOMATIC TRANSFER SWITCHES 16621-2

2. Transfer switches are to be rated for total system transfer on emergency systems.

3. Ratings shall be with non-welding of contacts during the performance of the withstand and closing tests.

B. Markings:

1. Markings shall be in accordance with UL 1008.

2. Markings for the additional withstand test hereinafter specified are waived when the testing laboratory is other than UL.

C. Tests:

1. Transfer switches shall be tested in accordance with UL 1008. The contacts of the transfer switch shall not weld during the performance of the withstand and closing tests.

2.3 HOUSING:

A. Enclose transfer switches in steel cabinets in accordance with UL 508, or in a switchboard assembly in accordance with UL 891, as shown on the drawings.

Enclosures shall be NEMA 3R with cabinet heater and thermostat for exterior applications.

B. Doors: Shall have three-point latching mechanism where required.

C. Padlocking Provisions: Provide chain for attaching a padlock. Attach chain to the cabinet by welding or riveting.

D. Finish: Cabinets shall be given a phosphate treatment, painted with rust inhibiting primer, and finish painted with the manufacturer's standard enamel or lacquer finish.

2.4 FEATURES: Transfer switches shall include the following features:

A. Operating Mechanism:

1. Activated by an electrical operator.

2. Electrically and mechanically interlocked so that the main contact cannot be closed simultaneously in both normal and emergency position.

3. Normal and emergency main contacts shall be mechanically locked in position by the operating linkage upon completion of transfer. Release of the locking mechanism shall be possible only by normal operating action.

4. Contact transfer time shall not exceed six cycles.

5. Do not use as a current carrying part. Components and mechanical interlocks shall be insulated or grounded.

B. Contacts:

AUTOMATIC TRANSFER SWITCHES 16621-3

1. On switch sizes 400 amperes and larger, protect main contacts by separate arcing contacts and magnetic blowouts for each pole. Arc quenching provisions equivalent to magnetic blowouts will be considered for approval.

2. Current carrying capacity of arcing contacts shall not be used in the determination of the transfer switch rating, and shall be separate from the main contacts.

3. Main and arcing contacts shall be visible for inspection with cabinet door open and barrier covers removed.

C. Manual Operator:

1. Capable of operation in either direction under no load.

2. Capable of operation by one person.

3. Provide a warning sign to caution against operation when energized.

D. Replaceable Parts:

1. Include the main and arcing contact individually or as units, relays, and control devices.

2. Switch contacts and accessories are to be replaceable from the front without removing the switch from the cabinet and without removing main conductors.

E. Sensing Relays:

1. Provide voltage sensing relays in each phase of the normal power supply.

2. Provide a voltage frequency sensing relay in one phase of the auxiliary power supply.

2.5 ACCESSORIES: Transfer switches shall include the following accessories:

A. Indicating Lights:

1. Provide a signal light for normal source position.

2. Provide a signal light for emergency source position.

3. Lights shall be different colors.

4. Provide laminated black phenolic nameplates with white letters to indicate transfer switch position.

B. Manual Test Switch: Shall simulate normal source failure.

C. Engine starting contacts.

D. Time Delay Relays:

1. Provide time-delay relays to accomplish the function as specified below and on drawings.

AUTOMATIC TRANSFER SWITCHES 16621-4

E. Auxiliary Contacts:

1. Provide contacts for connection to controls, one closed when transfer switch is connected to normal, and one closed when transfer switch is connected to emergency.

2. Provide additional contacts as necessary to accomplish the functions shown on the drawings, specified, and designated in other sections of these specifications.

3. Contacts shall have a minimum rating of ten amperes and be positive acting on pickup and dropout.

F. In phase monitor or center neutral position with time delay in neutral when switch controls motor larger than 10 HP.

G. Automatic Exerciser:

1. Clock exerciser for use with load.

2. Exerciser for use without load.

H. Automatic Transfer Switch AC Meter package: Provide an AC Voltmeter, an

Ammeter, and a Frequency meter. Meters shall be 2.5 inch, with 2% accuracy.

Provide a phase selector switch to allow reading voltage and current line to line or three phase. Meters shall read either normal or emergency source. Meter package shall be provided on each automatic transfer switch.

2.6 TRANSFER SWITCH OPERATION:

A. A voltage decrease in one or more phases of the normal power source to less than

70 percent of normal shall initiate the transfer sequence. The transfer switch shall start the engine-generator unit after a time-delay of two or three seconds to permit override of momentary dips in the normal power source. The time-delay shall be field adjustable from 0.5 to 6 seconds and factory set at 1 second.

B. The transfer switch shall transfer the load from normal to emergency source when the frequency and voltage of the engine-generator unit have attained 90 percent of rated value.

C. Unload running time delay for emergency generator cool down. The time delay shall be field adjustable from 0 to 5 minutes and factory set at 5 minutes.

D. Retransfer to Normal (All Loads): Transfer switch shall retransfer to normal source upon restoration of normal supply in all phases to 90 percent or more of normal voltage, and after a time-delay. Time-delays shall be field adjustable from five to twenty-five minutes (preset for twenty-five minutes). Should the emergency source fail during the timing, the transfer switch shall immediately transfer to normal when the source is available.

E. Transfer to Emergency (Emergency System Loads): Transfer switches for emergency system loads shall transfer their loads from normal to emergency

AUTOMATIC TRANSFER SWITCHES 16621-5

source when frequency and voltage of the engine-generator unit have attained 90 percent of rated value. Only those switches with deficient normal source voltage shall transfer.

F. Transfer to Emergency (Equipment System Loads): Transfer switches for equipment system loads shall transfer their loads to the generator on a time-delayed staggered basis, after the emergency system switches have transferred. Total delayed transfer time of an equipment system switches shall not exceed two minutes. Time-delay relays shall be field adjustable from zero to two minutes.

PART 3 - EXECUTION

3.1 INSTALLATION:

A. Installation shall be in accordance with the NEC and as shown on the drawings.

3.2 SPARE PARTS: Furnish the following:

A. Six spare control fuses of each rating.

B. Six spare pilot lamps of each type used.

3.3 TESTING:

A. When the complete system has been installed, and prior to the final inspection, test all components of the system in the presence of the engineer for proper operation of the individual components and the complete system and to eliminate electrical and mechanical defects.

B. When any defects are detected, correct the defects and repeat the test as requested by the engineer, at no additional cost to the Owner.

3.4 INSTRUCTIONS AND FINAL INSPECTIONS:

A. At the final inspection in the presence of the engineer, demonstrate that the complete auxiliary electrical power system operates properly in every respect.

B. Furnish the services of a competent, factory-trained engineer or technician for one four hour period, for instructing personnel in operation and maintenance of the equipment, on a date requested by the engineer.

END OF SECTION 16621