63
Fig. 95 — Two-Stage, 6-Element Electric Heat
SCR Controlled Electric Heat
If the OAT is below OAT heating setpoint, heating will be initiat
-
ed. The SCRs will control to a LAT of 72°F.
Units equipped the optional SCR controlled electric heat will
utilize a SCR power control, see Fig. 97 and 98. This power
control will convert a 0 to 10 VDC input signal from the 62X
controller to vary the heater output to maintain the desired
leaving-air temperature (LAT). The power control has a DIP
switch configuration for the type of input signal. See Table 29 for
proper switch settings.
Table 29 — Power Switch Settings
24V CONTROL
CIRCUIT
C
W1
W2
BLACK
WHITE
WHITE/
BLACK
TERMINAL BLOCK
AIR PRESSURE
SWITCH
HEATER
ELEMENT
HEATER
RELAY
MANUAL
RESET
LIMIT
MANUAL
RESET
LIMIT
LIMIT
SWITCH
(AUTO)
HEATER
RELAY
HEATER
ELEMENT
MANUAL
RESET
LIMIT
MANUAL
RESET
LIMIT
POWER TO UNIT
TERMINAL
BLOCK
GROUND
GROUND
L1
L2
L3
3 PHASE 60 CPS
SUPPLY
MAIN
TERMINAL
BLOCK
INPUT SIGNAL
SWITCH
#1
SWITCH
#2
SWITCH
#3
SWITCH
#4
0 to 10 Vdc Control
Signal (2 to 10 Vdc
Control Range)
Off
Off
Off
On