E1L/H1L. Ls With Electric/Hydraulic Override - Linde HPR-2 Manual

Controllers. E1L/H1L. Load Sensing with electric / hydraulic override
In addition to the load sensing function, HPR-02 pumps with H1L or E1L controllers offer the possibility of overriding the ∆p
LS-signal hydraulically or electrically. This enables a so called mode control for selecting different operating points or enables a
power limit regulation (underspeed control). The integration of all functions in the pump controller enables direct signal transfer
without delay. The controller-specific data are independent of the nominal pump size.
Possible applications of the LS signal override
>> Mode-control
A mode control (mode selection) modulates electrically the ∆p LS-signal at an orifice (e.g. directional control valve). The current
∆p LS value is reduced proportionally or in steps and the pump output adjusted via the pressure reducing valve (see the diagrams
on following pages.) In this way the volume flow of the pump can be reduced using the same orifice. In applications with propor-
tional valves this leads to enhanced control resolution, enabling particularly precise and sensitive actuator movement.
>> Power limit regulation
Any reduction in the prime mover speed is detected in conjunction with an electronic control unit, and the pump's volume flow is
limited through modulation of the ∆p LS value to ensure that the maximum power capacity is not exceeded. The maximum prime
mover power is thus available at all times, irrespective of ambient influences and the number of actuators.
In principle, the ∆p LS value acting at the LS-pilot can be modulated down to zero, whereas modified response times of the pump
system should be expected in the operating range near zero.
E1L/H1L-characteristic curve
2
∆p
1 Flow
2 Pressure
Maximum performance range of the pump
Actual power demand of the system
Mechanical ∆p basic setting
Effective, modulated regulating ∆p
Pump volume flow at fixed orifice (e.g. direc-
tional control valve opening)
1
Q
max
∆p
23