Gasboy Electric Keytrol - Manual (Page 8)

GASBOY Electric Keytrol
2-2 03/28/03
ANTI-FALSE COUNT ON STARTUP
A time delay relay is used to prevent a false count during startup (See figure below). If the pulser
is open, no count occurs upon start-up since the circuit is open. When the pulser is in a closed
position, Relay K2 (the time delay relay) is energized and its contact (K2-1B, which is normally
closed) is open, again preventing a count.
Upon receiving pulses from the pulser, the relay will drop out in 50 milliseconds. The next pulser
closure causes current flow through the normally closed (NC) contact, and actuates the totalizer.
Fifty milliseconds later, while the pulser is still closed, K2 (or Ktd) energizes, its contact opens,
dropping power to the totalizer, thereby reading the fuel in 0.1 gallon increments and not one-half
counts as other devices are prone to do. The 50 millisecond delay of the relay permits a
maximum pumping rate of 60 gpm (227 liters) dispensing and totalizing in 0.1 gallon (or whole
liter) increments.
MISSING PULSE DETECTOR (MPD)
Not available on Split Dual Pump Control Units The Missing Pulse Detector (MPD) circuitry
senses pulses from the pump pulser. If no pulses are received after the key is inserted and turned
in the Electric Keytrol within a preset time, the main power relay will open and an alarm will sound.
The alarm will continue to sound until the key is turned off, whereby the MPD circuitry is reset.
This circuit is primarily designed to prevent dispensing of fuel if the pulser is not functioning
properly. This could be due to a broken cable or shaft linking the pulser to the computer, or a
broken wire from the pulser to the Electric Keytrol.