ScopeOfWork.pdf

1. GENERAL

Furnish two (2) identical rotating cam limit switch systems each contained in NEMA 4X rated stainless steel enclosures. The limit switch systems will replace existing limit switch assemblies and enclosures on the lock tainter gate located at Upper St. Anthony Falls Lock.

The following existing limit switch reference drawings are included as attachments:

M-LSTA-24/510 SKEW CONTROL AND POSITION DEVICE DETAILS SHEET I

M-LSTA-24/511.1 SKEW CONTROL AND POSITION DEVICE DETAILS SHEET II

The new rotating cam limit switches will replace the existing items MARK 24/511-4 as indicated on the attached drawings. The new limit switch enclosures will mount in the same location as the existing limit switches. The existing external reducers and couplings will be reused. The existing limit switch enclosure mount brackets will be modified as required to attach to the new enclosures.

2. REFERENCE SPECIFICATIONS

NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum).

NEMA ICS 5 Industrial Control and Systems: Control-Circuit and Pilot Devices.

3. FEATURES

The limit switch systems shall be a rotating cam type similar to GEMCO 1980 series

(FIGURE 1).

Figure 1 - similar GEMCO 1980 rotary limit switch (six cam wheels shown)

Each cam limit switch system shall include sixteen (16) independent circuits with eight (8) cam wheels and eight (8) double pole double throw electric switches. All metallic parts of the enclosures and limit switch systems shall be corrosion-resisting metal unless noted, including shafts, bolts, nuts, screws, latches, pins, washers, and bushings.

3.1 Input Shafts

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SCOPE OF WORK

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Furnish 3/4" diameter symmetrical input shafts on both the right and left end of each enclosure. Shaft penetrations through the enclosures shall include water tight lip seals and/or sealed antifriction bearings as approved. Rotating shaft supports shall be mounted sealed antifriction type cartridge bearings that are not required to be stainless steel.

3.2 Enclosures

Enclosures shall be all stainless steel rated NEMA 4X. Case shall be fabricated from 1/8-inch thick welded stainless steel plates. Enclosures shall have an easily removable access cover held in place by adjustable tension stainless steel undercenter draw latches or similar stainless steel captive fastener system as approved. The joint between the case and cover shall be sealed with a neoprene gasket, securely bonded in place and designed to not stick to the opposing surface. Enclosures shall be equipped with an internal 25 Watt anticondensation heater energized continuously, no thermostat. Provide symmetrical 1.5 NPT tapped cable penetration bosses with threaded plugs both sides of each enclosure.

Provide 2 (two) ¼-20 welded studs, one the outside and one on the inside for making ground connections.

3.3 Switches

Insulating shields shall be provided where necessary to prevent arcing between parts. All switch setpoints shall be field-adjustable to occur anywhere within one revolution of the cams. Cam wheel diameter shall be at least six-inches. Cams shall be aluminum or bronze construction (plastic not acceptable). Switches shall be of the quick-make and quick-break type, shall have a pilot and control circuit contact rating designation of A600 at 600 volts a-c in accordance with NEMA ICS 5, and shall be assembled or combined into operating units as indicated. Switches shall include screw terminal block for connecting the external conductors. Each cam wheel shall have permanent radial hatch marks at one-degree increments with degree callouts at 20 degree increments in both rotation directions. The tripping mechanism shall be designed to pass the switch elements without harm if the element cam is not in the proper operating position and shall reset the contacts when moving in the reverse direction.

3.3.1 Spare SPDT Switches

Furnish sixteen (16) spare double pole double throw electric switches to be used as direct replacement spares. Spare switches shall have identical specification to those furnished installed in the enclosures.

3.4 Trip and Reset Accuracy

The design of the switch elements and operating mechanism of the limit switch shall provide for uniform and accurate setting. Repeatability of the action of switch contacts for normal range and extreme travel limits of the gate shall be with ± 1.0 degree of rotation of the external input shaft of the switch assembly. The tainter gate system is mechanically linked to the limit switch through an existing gear reducer so that the entire up and down cycle operation of the tainter gate will take place in less than one revolution of the limit switch cam wheels. Furnish cam wheels to allow the dwell configurations indicated on reference drawing M-LSTA-24/511.1.

4. SUBMITTALS

The following items shall be submitted for Government approval and Government approval is required before fabrication begins. Allow one week (5) business days, turnaround time for submittal / approval cycle. Forward submittals directly to:

US ARMY CORPS OF ENGINEERS

ATTN: DAROLD SANDERSON

180 5TH STREET E

SUITE 700

ST PAUL, MN 55101

651-290-5624 darold.b.sanderson@usace.army.mil

4.1 Submit dimensioned shop drawings to include enclosure dimensions, internal component layout, shafts, latches, and other details as required to verify compliance with these specifications.

4.2 Submit catalog information for all enclosure components including cams, switches, heaters, bearings, seals.

4.3 Submit operation and maintenance manual to include parts list, switch specifications and switch adjustment procedures.

5. DELIVERY AND SHIPMENT

Limit switch systems shall be delivered on or before 1 November 2013. Shipment address and shipment point of contact is:

US ARMY CORPS OF ENGINEERS

UPPER SAINT ANTHONY FALLS LOCK AND DAM

ATTN: DICK POLTA

1 PORTLAND AVENUE

MINNEAPOLIS, MN 55401-2528

(612)333-5336

5.1 Shipping

The bid price shall include the cost of transportation to the above address. Shipment shall be prepaid and made at the Contractor's expense. The Government will unload parts from the Contractor's delivery truck, with all other shipping and handling costs to be borne by the Contractor. The Contractor shall notify the Lock at least the day before the date on mailto:darold.b.sanderson@usace.army.mil which he expects to make delivery. Delivery shall be between the hours of 8:00 A.M. and 3:00 P.M. Monday thru Friday, except on Government holidays. Any delivery arriving after 3:00 P.M. will not be serviced by Government personnel until the next work period as designated above.