21
Midco International Inc.
8471 95
Part 2 Service - SCEBM-2 Module 120V
The SCEBM-2 Module ( for 120V Burners) is designed to control the speed of the combustion
blower based on three input signals and several programmable parameters.
-
The
inputs:
a. 2-10V DC control signal
i.
Controls the speed of the combustion blower whenever the burner is in run mode.
ii. There needs to be at least 2.0 V DC signal to this input in order for the burner to
turn
on.
b. Main valve input
i.
When power is supplied to the main valves it is also supplied to the SCEBM-2 control.
Along with the pilot valve input, this determines what mode the burner is in.
c. Pilot valve input
i.
When power is supplied to the pilot valve(s) it is also supplied to the SCEBM-2 control.
Along with the main valve input, this determines what mode the burner is in.
Inputs
Application Pilot Main Display Relay PWM Output
Intermittent O
ff
O
ff
PRGE Open 100%
Pilot
On O
ff
PIL
Closed Min
On On RUN Open Modulate
O
ff
On ERR Open Min
Interrupted O
ff
O
ff
PRGE Open 100%
Pilot
On O
ff
PIL
Open Min
On On IGN Open Min
O
ff
On RUN Open Modulate
PRGE=Purge mode. Before the burner starts or after the burner
stops, the combustion blower is modulated to high speed to purge the
combustion chamber with air.
PIL=Pilot mode. The period where the pilot valve is on but the main
valve is not on yet during which the pilot
fl
ame is established. In this
mode the combustion blower is modulated to low speed.
IGN=Ignition mode. On interrupted pilot systems, the time where both
valves are open is the period where the main
fl
ame is ignited by the
pilot
fl
ame. During this time the combustion blower will remain at low
speed.
RUN=Run mode. After the ignition sequence is complete, the burner will
be in run mode. Only in this mode will the combustion blower modulate
based on the 2-10V DC temperature control signal.
_____________________________________
XIII SCEBM-2
Module
120V Burners
Table 4
- SCEBM-2 Modulating Settings for 120V Burners