Publication of TM , 3 May supersedes FM , Theater of Operations Electrical TM is identical to that of the superseded FM 5- Field Manual (FM) , “Theater of Operations Electrical Systems, ” is intended for use as a training guide and reference text for engineer personnel who are. *This publication supersedes TM , 23 August , and FM , 9 October Field Manual. No. Headquarters. Department of the Army.
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When you connect a load between a live wire and a ground wire, any unbalanced current power in the line conductors is supplied through the ground wire. You must select generator sets that are the proper size and type for the field unit’s needs.
One method of doing this at each box is to touch the neutral wire and the box to the two ends of the tester. As outlined in Chapter 3the inspection checks include normal operation and operation under the rated load.
Any malfunctions that are beyond the scope of the operator or the crew must be reported to organizational maintenance. The inside surface is enameled to protect the wire insulation and minimize friction when pulling wire.
Glue the conduit together with gray conduit cement; do not use water-pipe cement.
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If the above materials are not readily available, use any available material. For vm single-phase connection, divide the total load equally between the three live wires.
Factory-made bends are available as an option rather than bending conduit on the job. Table describes the characteristics of four types of soils.
A maintenance shop that uses large amounts of single-phase and three-phase power requires a three-phase generator set. Impregnated-asbestos and varnished-cambric, flame-resistant cotton braid. After cutting PVC, trim the ends inside and out with a pocketknife to remove any rough edges that might damage conductor fmm.
Drill holes with a star or carbide drill, install expansion anchors, and secure the straps to the surface with machine screws.
Place No Smoking signs at each entrance to the fuel supply area, at least 50 feet from the fuel supply and the generator set. You have just completed a circuit from the distribution center to a new light fixture, and you need to test the circuit before turning on the breaker.
To avoid the possibility of short circuits, the maintenance organization responsible for power distribution in an electrical system should periodically spot-check the electrical fittings. Motor-driven, pipe-threading machines are also available for large installations and when threading a considerable amount of conduit. In comparison to the other wiring systems, it ranks behind rigid conduit but ahead of the other types of wiring when considering the quality and durability of the installation.
The sum of the inductive and noninductive loads is the connected load for the entire installation. They are classified by the manufacturers as follows:. For a long-term installation, consider placing the fuel tanks underground. Install the grounding rod in the hole, connect the grounding strap, and fill the hole with soil. Unbalancing causes high voltage on the lightly loaded phase and low voltage on the other phase s.
After all generator sets are operating in parallel, divide the load equally among them.
This will eliminate unnecessary vibrations. Turn all power off before reconnecting the generator sets. All load utilization devices fixtures and receptacles operating at line-to-neutral voltage in a grounded neutral system must be connected to both a white and a black or substitute color wire.
A single-phase, two-wire distribution system Figure has one of the two wires from the generator set connected to the neutral wire. Since it is important to maintain these protective coatings or shields on the wire conductors, ensure that preventive maintenance includes periodic tests and checks to expose potential trouble locations where the wire insulation has become frayed or where protective devices have been damaged. The foundation must be less than 6 inches high.
If a large amount of conduit is being cut, a power hacksaw is recommended. If the set is not attached to a pallet, use planks, timbers, logs, ammunition boxes, or other materials to prevent the skids of the frame from sinking into soft earth. This conduit, as its name implies, has a thinner wall than rigid conduit but has the same interior diameter and fmm area. Tile or Other Hollow Material. Parallel-connected generator sets are shown in Figure Demand factors Structure Demand Factor Housing 9 Aircraft maintenance facilities 7 Operation facilities 8 Administrative facilities 8 Shops 7 Warehouses 5 Medical facilities 8 Theaters 5 Navigational aids 7 Laundry, ice plants, and bakeries 10 All others 9.
Thin-wall conduit is more easily installed than rigid conduit. The radius of the curve on the inner edge of dm field bend must be at least six times the internal diameter of the conduit for rubber- braid- or thermoplastic-covered conductors and at mf 10 times the internal diameter of the conduit for lead-covered conductors. When the set is mounted on a trailer, it is called a power unit Figure Continued operation may cause serious damage.
Operators can test a generator set with the equipment it was designed to power or with a load bank.
The height includes 1-foot openings around the top of walls that are 3 feet high. Provide a suitable foundation so the generator set can be bolted to the floor. Excessive amounts of dust or moisture on equipment surfaces act as an insulator and prevent the heat from dissipating into the atmosphere through the equipment housing.
The white wire is always the grounded neutral wire. Map the field unit. Threaded couplings are furnished with each length of rigid conduit.
FM Theater of Operations Electrical Systems – Table of Contents
Modern Engine Blueprinting Techniques. For example, a dining facility may contribute about 25 percent of its actual electrical load to the peak load of the system. Motors built for especially low speeds or high torques may require more running current, in which case the nameplate current rating should 5–424 used.
Generator sets are shut down and serviced periodically.
Never use improperly operating equipment. Attach the grounding system with a No 6 AWG or larger cable. Grounds of this type are generally more difficult to locate than solid grounds.