Cleaver-Brooks CBH 40 - Sequence of Operation - CB-20 - Oil or Gas; Sequence of Operation - CB-40 - Oil or Gas

Chapter 3-Sequence of Operation
PROGRAMMING SEQUENCE FOR CB20 PROGRAM RELAY
BAR INDICATES TERMINAL ENERGIZED
40 50 60 70 80 90 1 00 11 0
PREPURGE-----------------
IGN.
PILOT
FIGURE 3-1.
PROGRAMMING SEQUENCE FOR CB40 PROGRAM RELAY
TERMINAL
ENERGIZED 0
SHADED BAR INDICATES TERMINAL ENERGIZED
1 0 20 30 40 50 60 70 80 90 1 00 11 0 120
PREPURGE----------------~
IGN.
PILOT
FIGURE 3-2.
High limit pressure or temperature control
(HLC)
Low
water cut-off (LWCO)
Low fire switch (LFS)
Auxiliary switches (AS-1) (AS-2)
100 and 200 series only
Gas-oil selector switch (GOS) 200 series only
High-low fire control (HLFC)
Damper positioning switch (DPS)
The controls used in the running interlock circuit
are:
Blower motor starter interlock (BMSI)
Combustion air proving switch (CAPS)*
*Not used on some 100 series
3-2
C. SEQUENCE OF OPERATION -
Oil or G~s
Applicable to a standardly equipped boiler with
CB-20 flame safeguard and program control
system.
This sequence covers burner operation from start-
up thru shutdown. No attempt is made to correlate
the action of the fuel supply system or feedwater
system except for those controls that directly affect
the action of the programming relay. Refer to the
wiring diagram supplied for this boiler in following
this sequence.
NOTE: The legend on the timer dial (Figure 1-3)
indicates the position of the timer and the
stage reached in the burner operating
cycle. The bar-graph shown in Figure 3-1,
or on the wiring diagram, indicates the