MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-11 - Manual (Page 18)

Model 505.07/.11 SilentFlo™ HPU 18
Auto-Cooling Valve (adjustable)
Introduction
Auto-Cooling Valve (adjustable)
The auto-cooling function is integrated into the control manifold. During periods
of low flow demand from the external hydraulic circuit, this feature provides two
important benefits: a re-circulating flow that ensures hydraulic fluid filtering
whenever the unit is on, and safeguarding against hydraulic fluid over-
temperature. It functions by opening a hydraulic flow path through the fluid
conditioning circuit when external hydraulic demand for flow is low. When the
external demand increases, this feature closes the path to provide the full flow of
the HPU to the external demand.
The effective operating range of the auto-cooling circuit is between system
pressures of 14 MPa (2000 psi) to 21 MPa (3000 psi). In order for the Auto-
Cooling Valve to function properly, it must be re-adjusted anytime the output
pressure will be changed for longer than 10 minutes.
Note If the test condition requires a maximum pressure level less than 14 MPa
(2000 psi), consult MTS.
Electrical Control
The HPU can be controlled locally using the front panel controls, or remotely
through a controller via the J1 connector. The controls included in the electrical
enclosure include the following:
• A start/low/high switch ensures that the system starts in low pressure, and
permits quick selection of low or high pressure. Wye-delta starting (505.11
only) reduces the initial current rush to the motor when electrical service to
the HPU is turned on.
• Thermal overload indicators protect the HPU from excessive current draw.
• A latchable Stop button prevents inadvertent starts.
• Interlocks protect the HPU against low hydraulic fluid level,
overtemperature, and dirty filters.
• Front panel indicators provide a quick indication of the unit’s condition.
These include power on, low level, overtemperature, and dirty filter lights.
– A Reset button brings the unit back into operation after a fault has been
detected and corrected.
– A dirty filter signal will not shut the unit down, but will prevent the
unit from starting.
• An hour meter is provided to help you determine maintenance intervals.
• The power disconnect switch on the door of the electrical enclosure ensures
that power is removed whenever the door is opened. It is a lockable, main-
disconnect switch.