KM SVS2000, Installation & Operation Manual, Page: 50 / 89

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97-1129-01 Rev. D
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Track
Setpoints can be set to energize based on tracking the gross weight (Grs), net weight (net),
total weight (Tot), or a system fault (Flt). Energizing based on the gross weight is the default.
note: If Track is set to Flt, the setpoint remains energized except in a fault condition or if
power is turned off.
Failsafe
If the SVS2000 detects a problem, one of three fail-safe conditions can be applied to a
setpoint:
• On
• Off — default
• nC (no change)
On energizes the setpoint in a fail-safe condition. Off de-energizes the setpoint in a fail-safe
condition. nC makes no change to the setpoint in a fail-safe condition (i.e., if it was energized
before the problem was detected it will continue to be energized). A fail-safe condition
remains in effect until the problem has been corrected. The following are examples of fail-safe
conditions:
• ADC (analog-to-digital converter) overrange/underrange condition
• engineering units overrange
• Communication error with a serial device
Preact
Determines the point before Value is reached at which a setpoint is energized. Preact provides
the ability to take into account the time required for the setpoint and associated control
equipment to respond. Preact equals the amount of material that will be added to or removed
from the vessel after the setpoint is energized. The default is 0.
SeTpoInT exaMple
See Figure 11. A vessel with a 9,100 lb capacity has Relay 1 Value set at 9,000 lbs gross weight (Track is Grs).
The Hi/Lo function is set to Hi. This relay controls the closure of a valve to stop material flow into the vessel.
However, after the valve closes, the material still in the inclined pipe continues to flow into the vessel. Preact
is set to 20 lbs to take account of the material in the pipe, so the maximum material weight in the tank will not
exceed 9,000 lbs. (note that the same operational effect can be achieved by setting Value to 8,980 lbs and
Preact to 0 lbs.) Deadband is set at 1,000 lbs. When the contents exceed 8,980 lbs (9,000 lbs minus the 20 lb
preact), the relay energizes, closing the valve to stop material flow into the vessel.
The valve remains closed until the relay deenergizes at a material weight of 7,980 lbs (8,980 lbs minus the 1,000
lb deadband). This vessel has Relay 2 Value set at 2,000 lbs gross weight (Track is Grs). The
Hi/Lo function is set to Lo and the Deadband is set at 500 lbs. When the contents falls below 2,000 lbs, the relay
energizes, activating a pump to fill the vessel. The pump continues to operate until the relay deenergizes at a
material weight of 2,500 lbs (2,000 lbs plus the 500 lb deadband).