MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-180 - Manual (Page 77)

Recovering From an Interlock
Model 505.60 - 505.180 SilentFlo™ HPU Operation 77
Click on the HPU Status button to display the HPU Status screen and identify
the fault conditions (see the next figure).
Hyd fluid low level
The HPU Fault Status on the user interface panel displays Hyd Fluid Low
Level when the hydraulic fluid falls below the setting of the low level/over
temperature sensor mounted through the top of the reservoir. Perform the
following steps to correct a low level interlock:
1. Determine the cause for the low fluid level and correct it.
2. Add hydraulic fluid to the reservoir until the sight glass on the side of the
HPU indicates the proper level.
3. Verify that the hydraulic fluid level sensor is detecting the proper fluid level
by selecting the HPU Data screen and checking that Hyd Fluid Level
indicates Max
4. Press Reset to clear the interlock and change the unit status back to
NORMAL.
Hyd fluid
overtemperature
The HPU Fault Status on user interface panel displays Hyd Fluid Overtemp
when the temperature exceeds 55°C (131°F). The temperature is detected by the
low level/over temperature sensor mounted through the top of the reservoir. The
HPU cannot be restarted until the fluid has cooled. Perform the following to
correct an over temperature interlock:
1. Check the actual temperature of the hydraulic fluid by selecting the HPU
Data screen and checking Hyd Fluid Temp on the display.
2. Determine if the hydraulic fluid is receiving adequate cooling.
• The cooling water inlet temperature affects the efficiency of cooling
the hydraulic fluid.
• Check the cooling water inlet-to-outlet pressure differential. It should
be between 0.24–0.31 MPa (35–45 psi). If necessary, adjust the water
pressure at its source.
3. If necessary, cool the hydraulic fluid by circulating hydraulic fluid through
the heat exchanger.