USER MANUAL
600U Ultra Flame Rod
Signal Processor
APPLICATION
The Honeywell 600U Ultra flame rod signal processor is a
reliable flame monitoring system based on the proven
principle of measuring rectified current flow through a flame
rod when a flame touches it. An AC voltage of 175 VAC is
applied to the flame rod; when a flame touches the rod, a
rectified current flows from the rod through the flame to the
ground of the burner. The 600U controller measures the
rectified current and energizes the flame relay if the current
exceeds the value for the flame-on setpoint. If the current flow
drops below the value for the flame-off setpoint, the flame
relay de-energizes. A visual display indicates whether or not
the flame relay is on and the relative signal strength, i.e., the
DC current flow through the flame.
The 600U is also capable of driving either (a) an ignition coil or
(b) an ignition transformer. (a) The ignition coil would be part
of an ignitor assembly; when using the ignition coil, the flame
rod which is used for sensing flame serves also as an ignition
rod. (b) AC power to an external ignition transformer is
switched on by a power relay in the 600U controller when an
ignition signal is applied. In this case, the high voltage from
the ignition transformer cannot be applied to the flame rod; a
separate ignition rod is required.
An AC or DC signal is applied to the 600U controller to turn on
the ignition coil and the ignition transformer. When the signal
is applied, the 600U controller pulses the ignition coil at 50 or
60 times per second, depending on the line frequency. The
ignition signal also causes a power relay in the controller to
close, connecting the controller’s AC input voltage (after
fuses) to an external ignition transformer if one is hooked up.
While the ignition signal is applied, the flame relay is
de-energized.
By means of a jumper the sensitivity of the 600U to flame can
be changed. Four sensitivity levels are provided. The
sensitivity of the display and the values of the flame-on and
flame-off setpoints are all changed together by the jumper.
Various protection features are provided. The flame rod itself
can be shorted to ground indefinitely without harm to the unit.
If the flame rod becomes fouled so that an unreasonably large
amount of AC current flows from the flame to ground, first a
yellow “ROD FOULED” LED is turned on. If the AC current
increases further a “ROD FAULT” LED is turned on and the
flame relay is de-energized. Note that the 600U controller
distinguishes between AC current flow due to fouling and DC
current flow caused by the presence of a flame.
If a grounded person touches the flame rod, he will receive a
perceptible shock, but he will not be hurt because less than
.5 mA of AC current will flow. If the flame rod is also being
used as an ignition rod and the rod is pulsed by an ignition
coil, the shock will be strong but it should not be dangerous
because of the short duration of the pulses.
SPECIFICATIONS
ELECTRICAL
Primary Input Power: 85 to 132 VAC, or 170 to 264 VAC;
50/60 Hz.
Input Current (monitoring only): 0.07 A at 115 VAC, 0.035 A
at 230 VAC.
Input Current (ignition on): 0.3 A at 115 VAC, 0.15 A at
230 VAC; plus current to ignition transformer (5 Amps max-
imum.)
Ignition Command Input: 12 to 50 VDC or 85 to 264 VAC, 50/
60 Hz.; (using labeled DC and AC inputs).
Command Current: 0.02 A DC at 50 VDC, 0.015 A RMS at
230 VAC.
Maximum Capacitance Load: 1.0 nF, flame rod drive to
ground (through wire insulation).
