The C554A Cadmium Sulfide Flame Detector (cad cell) is
a photo conductive flame detector (see Fig. 1) used with
oil primary controls such as R4166, R4184, R8182,
R8184, R8185, R8404 and R8991. It consists of a plug-in,
light sensitive cell and a socket with Type E mounting
bracket, factory-installed leadwire and an oil line adapter
bracket. Leadwire length is 60 in. (1520 mm). The detector
is installed inside the air tube of the burner where the cell
can view the flame and is wired to the F-F terminals of the
oil primary control.
The photocell is a ceramic disk coated with cadmium
sulfide and overlaid with a conductive grid. Electrodes
attached to the ceramic disk transmit an electrical signal to
the primary control. In darkness, cadmium sulfide has a
very high resistance to the passage of electrical current. In
visible light, its resistance is very low and current is
allowed to pass. The entire cell is hermetically sealed
(glass to metal) to prevent cell deterioration.
Fig. 1. C554A Cadmium Sulfide Flame
Detector (cad cell).
When Installing this Product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a
2. Check the ratings given in the instructions and on
the product to make sure the product is suitable for
3. Installer must be a trained, experienced service
4. After installation is complete, check out product
operation as provided in these instructions.
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Cadmium Sulfide Flame Detector
Disconnect power supply before beginning
installation to prevent electrical shock or equipment
The burner manufacturer determines the cad cell location
(see Fig. 2). If an alternate location must be used, make
The cell has a clear view of the flame.
Ambient light does not reach the cell.
Ambient temperature at the cell location is below
140 F (60 C).
Movement, shielding, or radiation of metal surfaces
near the cell do not affect cell function.
Fig. 2. Cad cell location.
Remove the cell from the socket.
Insert the mounting bracket into the socket slot
(Fig. 3) as far as it will go.
NOTE: Bend the mounting bracket to fit, if