74
Troubleshooting Chart
Symptom
Possible Cause
Control unstable
(EngSpd mode); RPM
rate inconsistent with
selected rate - continued
• Bad RPM signal
• Servo Valve spool loose or incorrectly indexed
• Check inlet/outlet water temp delta T; optimum delta T is 60-100 degrees F
Absorber loses load
while testing
•
Insufficient water supply
• Inlet temperature too high (above 90 degrees F)
No load cell reading (no
torque measurement)
• Perform Torque Cal procedure
• Broken wires on load cell
• Load cell bad
Servo valve does not
move (manual mode)
• Cable disconnected
• Motor failure on valve
• Debris in valve jamming spool
• Electronics failure in sensor box
• Fuse blown
• 1200A-2540 board bad; check VSTEP and VSTEP2 LEDs
7.3 Water System
You should have a thermocouple installed to measure inlet and outlet water temperature on your system.
There are 1/8 MPT ports on each valve’s manifold. We typically like to see inlet water temperature no
higher than 90 degrees F.
The amount of water flowing through your absorber is determined by your inlet water pressure and the
ValPos
setting you are using. Higher water pressure will cause faster fill rates and push more water
through the absorber for a given servo valve opening. We recommend between 50-80 psig inlet water
pressures. You should monitor this pressure via one of the pressure transducer ports on the pressure
panel in your sensor box. If you do not have a transducer to use in your panel for this, but have an open
port, contact SuperFlow Customer Service to purchase a transducer and have your system configured to
read it.
The
ValPos
setting determines how much you are opening the inlet valve. A larger
ValPos
setting will
subsequently flow more water. The volume of water flowing through the absorber will have an effect on the
outlet water temperature. High flow rates will have lower outlet temps, and a low delta T between inlet and
outlet temperatures.
It is not uncommon to have outlet water temps in the high 180’s. We would prefer to see a
ValPos
setting
that would lower that temp slightly, if control is still acceptable. As we said earlier, the brake itself is very
robust and durable, but if internal water temp gets too high, it can flash to steam, and then load control is
totally lost, allowing the engine to run away.
It is also very important to insure your outlet water has a “free run” to the sump tank, without any
restrictions such as several 90 degree elbows. If water backs up against the absorber outlet, it creates back
pressure on the system, and this causes load control instability.
7.0 Troubleshooting
