Figure 2-21.--Relay enclosures.

overvoltage, reversal of current, excessive currents,

may set off a chain reaction of successively acting

and so on.

relays, which then perform various functions.

Control relays are also classified as open,

Control relays can also be used in so-called

semisealed, or sealed. Figure 2-21 illustrates the

lockout action to prevent certain functions from

various types of relays used today. Relays E, G, and

occuring at the improper time. In some equipment,

H are examples of open relays. The mechanical motion

control relays are used to sense undervoltage and

Figure 2-21.--Relay enclosures.

2-14