TM-9-2815-220-24 Maintenance Manual for AVDS-1790-2CA AVDS-1790-DA and AVDS-1790-2DR Engines Download
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TM 9-2815-220-24 WARNING SUMMARY WARNING Electric Shock Shock happens when the body becomes part of an energized electrical path and energy is transferred between parts of the body, or through the body to a ground or the earth. In order for shock to occur, a potential difference or stored electrical charge must be present to cause the current to flow. Current flowing through the highly sensitive central nervous system can, under certain conditions, cause serious injury or death. Some of the conditions, which govern the severity of a shock, are mentioned below. Type of current The type of current involved, alternating current (AC) or direct current (DC) is important. Low voltage, up to 40 volts of direct current (DC) circuits do not normally present a hazard to human life. Under some circumstances, however severe burns can result. Even at low voltage, alternating current (AC) circuits can be dangerous and present a lethal threat. At commercial frequencies (50-60 cycles or hertz) and intermediate voltages (50 to 600 volts), lethal current may be conducted through the body. Resistance The resistance of the body and the degree to which the skin is insulated from the ground govern the amount of current flowing through the body. The skin offers the principle resistance which the human body presents to the flow of current. If the skin is wet or moist, the resistance is lowered and therefore the greater flow of current and the severity of shock. Time The length of time the body is in the circuit is also important, particularly with respect to the severity of burns. Burns break down the skin, thereby lowering the resistance. The more extensive the burn, the less resistance provided. Time becomes critical when current flowing though the body causes loss of muscular control, contraction of the chest (which affects breathing), and ventricular fibrillation of the heart. When the last occurs, the heart's pumping rhythm becomes irregular and it ceases to function properly. Both the magnitude and path of the current flowing through the body are of primary importance. When the path of the current is hand-to-hand or hand-to-foot, vital organs (brain, heart, lungs, spinal cord) are affected, possibly with serious consequences. Emergency Measures for Shock Everyone engaged in any electrical or electronic work should be capable of carrying out the following measures: • Free the person involved from the live circuit. If a person is "frozen" to a live electrical contact, shut off the current if possible. If this cannot be done, use wood boards, poles, or sticks, a belt, piece of dry rope, an article of clothing, or any non-conducting material of sufficient length to pull the body away from the contact. Act quickly, and remember to protect yourself during this operation. • Cut off the power. Because of the dangers involved in being caught in a live circuit, know how to cut off the power anywhere in your work area, and how to summon help in case of an emergency. Administer cardiopulmonary resuscitation. c