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3. Motors—direct current motors draw several times their rated current during starting, and magnetic energy stored in their armature and field coils is released when the control switch is opened. 

Figure 4-118  is typical of those tables available for selecting the proper nominal switch rating when the continuous load current is known. This selection is essentially a derating to obtain reasonable switch efficiency and service life. 

Hazardous errors in switch operation can be avoided by logical and consistent installation. Two position on-off switches should be mounted so that the on position is reached by an upward or forward movement of the toggle. When the switch controls movable aircraft elements, such as landing gear or flaps, the toggle should move in the same direction as the desired motion. Inadvertent operation of a switch can be prevented by mounting a suitable guard over the switch. 

## Relays 

Relays are used as switching devices in which a weight reduction can be achieved or electrical controls can be simplified. A relay is an electrically operated switch and is therefore subject to dropout under low system voltage conditions. The previous discussion of switch ratings is generally applicable to relay contact ratings. 

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