Mohawk SSDG Specification.pdf

31120_WJW_0709_FLT

REC_31120_FLT_270’ WMEC

B Class(0210)

WORK ITEM 1: Ship Service Diesel Generator, Clean & Inspect

1. SCOPE

1.1 Intent. This work item describes the requirements for the Contractor to inspect, recondition, and test in place the windings of each Ship Service Diesel Generator.

1.2 Government-furnished property.

None.

2. REFERENCES

COAST GUARD DRAWINGS

None.

COAST GUARD PUBLICATIONS

Coast Guard Technical Publication (TP) 2820A, Manufacturer's Instruction Book – SWBS

Group(s) 311 Surface Forces Logistics Center Standard Specification (SFLC Std Spec) 0450, Jan 2009, Electrical Power for Contractor’s Tools & Equipment Surface Forces Logistics Center Standard Specification (SFLC Std Spec) 3100, Jan 2009, Inspect, Test and Recondition AC Synchronous Machines In-Place

OTHER REFERENCES

None.

3. REQUIREMENTS

3.1 General. Inspect, recondition, and test in place the windings of No. 1 and No. 2 Ship Service Diesel Generators in accordance with SFLC Std Spec 3100. Generator data is shown in Table 1 below.

3.2 Optional work. Perform the optional work sections of SFLC Std Spec 3100 as follows:

3.2.1 Bearing wear. Do not measure and record bearing wear.

3.2.2 Collector rings. Do not measure and record collector ring wear and concentricity.

3.2.3 Rotor extraction. Do not remove the rotor for cleaning within the compartment and reinstall it afterwards.

TABLE 2 – EXTERNAL HEATING DATA

Heater Power Machine Weight

(lbs) (kW) (BTU/h) Heatup Rate

(°F/h) Temperature

Rise (°F) Duration (h)

6,000 4.2 14,330 20 107 5.4

4. NOTES

4.1 Conditional performance. This work item is performed only when warranted by the condition of the generator windings. The mere presence of dust is not sufficient justification to perform this work item.

4.1.1 Note that there is some risk that solutions used during the cleaning process may penetrate through microscopic cracks in the varnish, carrying contaminants deeper into the windings through capillary action. Once so embedded, such contamination cannot be removed and insulation resistance could actually be degraded such that a costly and time consuming rewind would be necessary.

4.1.2 Cleaning is normally only warranted when the windings have been wetted by sea water or insulation resistance trends suggest that the machine will fall below the minimum acceptable insulation resistance for operation before the next depot level availability.

4.2 Shop cleaning. This generator is not removable from the vessel without making a hull cut. For machines that can be removed from the vessel through existing accesses or openings created by other work items, it is generally quicker and more cost effective to offload the affected generator from the vessel and perform the work ashore in a generator repair shop. Such tasking should be performed under “Ship Service Diesel Generator Overhaul” and not this work item.