Low/high pressure functionality, Low/high pressure functionality 83 – MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-180 User Manual
Page 83
Low/High Pressure Functionality
Model 505.60 - 505.180 SilentFlo™ HPU
Operation
83
Low/High Pressure Functionality
This section clarifies the low and high pressure functionality of the HPU. There
are certain cases where it is advantageous to use the HPU in low pressure versus
high pressure. Low/High functionality is illustrated in the block diagram below:
Low pressure
Series 505 HPUs are started in low pressure to reduce the amount of current
inrush at motor start-up. A solenoid valve that opens a direct flow path to the
return line commands the pressure setting. Since this direct path offers little
resistance to the full flow, minimal system pressure is developed (low pressure).
Low pressure operation of a Series 505 HPU provides several useful functions
when high pressure is not required by the external system.
System commissioning
Best practices for system commissioning include flushing the hard line and
related equipment. This process “conditions” the hydraulic fluid to a cleanliness
level that supports high performance servovalve systems. Refer to the Hydraulic
Fluid Care Guide (part number 050-000-536) for information on fluid
cleanliness.)
A logical progression of fluid conditioning that begins at the HPU is required to
minimize problems when commissioning a system.
•
With the HPU running in low pressure, acceptable particle counts are
obtained in a relatively short time.
•
Keeping the HPU in low pressure effectively isolates the external or system
flow because the relative back pressure is normally much higher in the
external system circuit.
•
Running the HPU in low pressure maximizes fluid flow, allowing the HPU
to circulate the reservoir contents across the filter more times per hour.
•
Starting the commissioning process with an isolated HPU reduces the
possible number of problems encountered during start-up.
Flow to External
System
Return Flow
from System
High Pressure
Flow
HPU Manifold
Low Pressure
Flow
Reservoir
Filter
Heat
Exchanger
Circulation
Pump