Page 100 - Electromechanical Devices and Components Illustrated Sourcebook

62 Electromechanical Devices & Components Illustrated Sourcebook

Element Fuses
Element Contactors
Primary Contactor

CONTACTOR CONTACTOR
60 HP / 90 AMP 20 HP / 30 AMP
24 VAC COIL 24 VAC COIL

Chassis Ground
CONTACTOR
20 HP / 30 AMP
24 VAC COIL
On/Off Switch

CONTACTOR
20 HP / 30 AMP
24 VAC COIL
Main Fuses

Internal Panel
Enclosure
Control Transformer
Primary Power (From Disconnect)

Figure 4-75 Electric Furnace
Controller

Upper Base
NC Terminal
knife switch relay shown in Figure 4-57. The principal differ-
Contacts
Return Spring ence is that the blade closes a contact when it is in the upright
Pivot Spacer Frame position. In this manner the relay has a normally open termi-
Link Pivot
nal and a normally closed terminal.
Link
Figure 4-77 shows a typical double throw relay. A relay of
this type may have as many as eight poles. These units are
Terminal NO Terminal
Base Lower Base available in a wide range of configurations and capacities.
They are often delivered with a protective plastic case which
Insulating Pivot
Solenoid Mount protects the mechanism from dust and dirt.
Solenoid Core Reed relays are commonly found in communication and
test equipment. These relays are essentially the same switch
as shown in Figure 4-19, except a solenoid replaces the push
button. They are often configured with a number of poles
designed for specific applications. Figure 4-78 shows a typical
Figure 4-76 Double Throw Knife Switch Relay commercial reed relay.