Make sure no vehicle is attached at power-up.
Note: The cable and plug connections shall be tested continues if an active storage hanger is used.
If all tests are passed the rack monitor is ready for use.
The first task of the 88XX Rack Monitor is to ensure proper grounding is established via Pin 9 and pin 10 of the plug
socket connection to the tank-truck chassis. Or a low impedance between the two jaws of the clamp (MODEL 7720)
or the pins of the plug assembly. (MODEL 7620). As soon as this has been ensured, two white Led indicators will
flash inversely or in case of the 88X4E the TOP light bar . (see Table 1 for light patterns)
Secondly the 88XX will check for shorts between sensors and shorts to ground and for open circuits for every
channel.
Then the 88XX Rack Monitor (887xE only) will determine sensor type and the amount of compartments. It can
detect up to eight Two-Wire sensors, up to 12 Five-Wire sensors and is fully compatible with the 3205E On board
Retain Overfill Monitor. If possible, the amount of sensors will be shown on the Display and Led indicators. (see
sensor detection chapter for details).
The 887xE Rack Monitor provides an “Auto switching” capability between 2-Wire sensors and 5-Wire sensors.
If sensor type is selected, all sensors are dry and proper ground is verified the 887xE Rack Monitor will
communicates a Permissive condition to the automation equipment. The monitor can only be connected to one type
of signal source at any one time. You cannot have a mix of 2 & 5-Wire sensors connected at the same time.
The 88XX Rack Monitor systems uses self-checking principles to provide a continuous check on all system
components. It depends on the dip switch setting if the detected shorts are of influence of the PERMISSIVE signal.
e.g. If the 88XX rack monitor dip switch is set to EN13922 then NO shorts between channels are allowed. If at any
time the 8800E Rack Monitor detects any kind of failure, a signal to the automation equipment will be send to shut-
off the flow. All sensor failures are indicated on the two possible displays. 88XX and 88X1
The 8851 is equipped with two simple multi-color light bars. Default factory setting of the light pattern is according
the light pattern of the 8130 rack monitor. (see Table 1 for details). A second light pattern can be set via dip
switch settings (see DIP Switch settings for details).
Relay Operation
This rack monitor is standard equipped with three relay outputs.
1. The normally open Permit relay will switch if all sensors are dry AND a good ground connection is detected.
2. The normally open AUX 1 relay is by default used as a secondary safety relay. This relay will switch on just
before the Permit relay switches on. When a wet sensor or bad ground is detected the Permit relay will
switch off and the AUX1 relay will switch off a fraction later. The physical state of the Permit relay is
monitored. The monitor will go into an error state if the Permit physical state of the relay differs from the
electrical state. The AUX1 relay will stay in the OFF position as long as the rack monitor is in this error state
until power has been switched off and on. Above sequence is built-in to detect and protect “burn-in” of
contacts during switching from permit to on-permit and v.v. (Connect both Permit and AUX1 in series to
increase functional safety.)
The AUX1 relay will be used for secondary shutdown if a second sensor detection PCB is placed.
In this case the secondary sensor detection is used for redundancy and contacts of AUX1 should be wired
separately to the terminal automation installation.
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