TGA300 Rev180405
16
Running Away From Water, Low Water, or No Supply Water
There are situations during pump operations when there may be low or no supply
water. This can be due to an empty water tank, a problem on the intake line, air in the
pump, changing the water source, or an insufcient water supply.
The governor constantly monitors discharge pressure and compares it to engine
RPM. It is programmed to limit RPM increases when conditions arise that fall outside
of normal operating parameters.
Running Away From Water: If the discharge pressure starts dropping while
operating in pressure mode, the governor increases the engine RPM and attempts to
maintain the selected pressure setting. If pressure drops and an increase in RPM does
not bring the pressure back up, the governor recognizes this as a running away from
water condition. When this condition occurs the governor switches to the RPM limit
mode and controls the engine RPM accordingly.
RPM Limit Mode: When the RPM limit mode is in effect the PRESSURE
LED stays on. To alert the operator the RPM LED and the RPM display ash, and the
message display ashes OPERATOR / RPM LIMIT. In this mode the pressure setting
does not change and the PRESET button is disabled. When the pressure comes back
up to the selected pressure setting, the RPM limit mode is canceled and the governor
switches to normal operation in pressure mode at the selected pressure.
In some cases the pressure may not come back up but remains at a level above 45
PSI. In the RPM limit mode, the governor behaves like a manual throttle and the operator
can raise or lower the engine RPM by pressing INC/DEC or rotating the control knob.
If the RPM is manually lowered to a point where the pump is not running away from
water and pressure is stable, the RPM limit mode is canceled. The governor switches
to normal operation in pressure mode with the current discharge pressure as the new
pressure setting.
If the engine is set to idle using the IDLE button, the governor comes out of RPM
Limit Mode and cancels the pressure setting.
Low Water Cycle: If the discharge pressure is below 45 PSI, but stays above 15
PSI, the governor enters a low water cycle and the message display ashes LO WATER.
It sets the engine at 1100 RPM. If the pressure does not rise above 45 PSI in 7 seconds,
the governor sets the engine RPM at idle. The governor repeats the low water cycle as
long as the discharge pressure is between 15 and 45 PSI. When the pressure rises above
45 PSI the governor resumes normal operation. (The values for RPM and PSI in the
low water cycle are programmable and may vary for some engine/pump combinations.)
No Supply Water: If the discharge pressure is below 15 PSI, the engine RPM
is set at idle and the message display ashes NO WATER. If, within 3 minutes, the
discharge pressure rises above 15 PSI the governor enters the low water cycle. If the
discharge pressure does not rise above 15 PSI within 3 minutes, the governor switches
to idle mode and cancels the pressure setting. To restart pump operations, the operator
must take action (press PRESET and/or INC/DEC or rotate control knob to select
pressure setting).
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