MTS Series 505G2 SilentFlo Hydraulic Power Unit Model 505G2-30 - Manual (Page 47)

Changing the Water Flow
Model 505G2.20 - 505G2.30 SilentFlo™ HPU Operation 47
2. If the there is no change in the Oil Temp reading after several minuets,
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. After the displayed fluid temperature drops below 55°C (131°F), press the
Stop button.
4. Press the Reset button to clear the interlock and turn the indicator off.
Watchdog Fault The HPU Fault Status on the user interface panel displays Watchdog Fault if
the watchdog timer stops operating properly. A watchdog fault causes the HPU to
shutdown. Perform the following procedure to attempt to recover from this fault.
1. Turn the power disconnect switch on the main enclosure to off.
2. Wait at least 60 seconds, then close the power disconnect switch.
3. From the Startup Screen, press the Main Display button.
4. On the Main Display screen, press the Reset button.
5. If the Watchdog Fault condition does not clear, contact MTS Systems
Dirty filter
A dirty filter interlock is indicated on the Main screen by a yellow Alarm
indicator and a blue Status indicator. Press the Status button to display the Status
screen and note the yellow Return Filter Dirty or Press(ure) Filter Dirty
indicator(s). The interlock is generated when the filter capacity has reached a
critical level. A dirty filter condition will prevent the HPU from being started, but
it will not stop the HPU while it is running.
1. Replace the dirty hydraulic fluid filter. Refer to procedures for return line
filter replacement and high pressure filter replacement as required.
2. Press Reset to clear the interlock and turn the indicator off.
Changing the Water Flow
The flow of water is the only way to maintain the temperature of the hydraulic
fluid. The water-regulating valve, located on the water inlet line of the HPU,
senses the hydraulic fluid temperature and automatically controls water flow to
the heat exchanger.
Note When the HPU is turned off, a solenoid valve also shuts off the flow of
water to the heat exchanger.