Installation manual

FuelMaster
®
Installation Manual
28
Relay Options
. An FMU may be thought of as a switch installed in a control circuit of a
dispensing device. It is installed where it can interrupt flow to each dispensing hose. When
authorization is provided, the FMU “closes the switch” to complete the circuit. Relays are used to
“close the switch”. FMUs may be ordered with 50 amp solid state relay assemblies or with dual
control relay assemblies. If a preference is not indicated on the sales order, most FMUs are
provided with the solid state relay assemblies. FMUs for small airport or marina self-serve retail
applications are provided with dual control relay assemblies to better accommodate two-stage valve
control for credit card presets.
• Solid State Relay Assemblies. The basic FMU contains a solid state relay assembly with two
relays. Additional relays are provided when additional hose controllers are purchased.
Though the solid state relay assemblies are rated for 50 amp current loads, other factors limit
their application. When used to control motors, the startup current load of a motor may be
significantly greater than the run current. 50 amp solid state relays should not be used to directly
control motors which exceed 1 hp 110 VAC or 1-1/2 hp 220 VAC.
When used to control other solid state devices, RC networks (sometimes referred to as
snubbers or spark quenchers) may be needed to remove transient voltages that provide false
indications of pump handle detection. If the solid state relay assembly is needed for other than
AC control, the voltage requirement must be specified. The relays must be changed for DC
voltages. Solid state relay assemblies are available with either AC (240VAC) or DC (24VDC)
relays, and relays of both types may be mixed within a single relay assembly.
24 VDC relay assemblies will have a 24 VDC ONLY label applied to the surface of the circuit
board, and will control any DC voltage from 3.5 to 32 VDC.
• Dual Control Relay Assemblies. Dual control relay assemblies were designed to control two
devices (i.e., solenoid valve and motor contactor) from a single control output. The dual control
relay assembly cannot directly control devices or circuits drawing more than 2 amps. If the
current draw exceeds 2 amps, contact starters must be installed to control the device (or circuit).
Dual control relay assemblies can control devices of any voltage, and a combination of such
devices may be mixed in a single relay assembly. The dual control relay assembly has four
relays in its standard configuration, but the basic FMU possesses only two hose switches.
• Automatic/Manual Mode Switch Differences. The automatic/manual mode switches for solid
state relay assemblies are not the same as for dual control relay assemblies. If a change is
made from one type of relay assembly to the other, the hose switches should also be changed.
Since the current carrying capacity of the solid state relay assembly is much greater than that of
the dual control relay assembly, the wires from the switches are of different wire gauge to
accommodate the greater current carrying capacity. Additional hose switches are provided when
additional hose controllers are purchased.
Prokee
®
The Prokee
®
is the FuelMaster
®
patented access device used to initiate a
transaction at the FMU. All Prokee
®
s are constructed alike with an eight-pin
read/write memory chip housed in a composite holder. Prokee
®
s attain their
identity as a Vehicle Key, User Key, Supervisor Key, Manual Issue Key, Lube
Truck Key or AIM2™ Programmer Key as they are encoded with the software
and encoder. For visual identification, Prokee
®
s are available in black, orange,
red, blue, and green.
• Vehicle Keys are encoded with a vehicle identification number and are
assigned to a vehicle.
Figure 2-2.
Prokee
®
204