You can either choose a single ramp (1 ramp time) or a 4-quadrant ramp (4 ramp times).
Characteristic curve generator [5]
Using the adjustable characteristic curve generator, step level and maximum values for positive and negative signals can be set separately, adjusted to the hydraulic requirements. The actual development of the characteristic curve through the zero point is not stepped but linear.
Amplitude limiter [6]
The internal command value is limited to approx. ±110 % of the nominal range.
Current controller [7]
The solenoid current is recorded, in the current controller compared with the control output and the difference is compensated.
Current output stage [8]
The current output stage creates the clocked solenoid current for the proportional valve. The solenoid current is limited to 2.7 A per output. The output stage outputs are short-circuit-proof. The output stages are de-energized in case of an internal fault signal or if the enable signal is missing.
Clock generator [9]
The clock generator creates the clock frequency “f” of the output stages. With pre-parameterized Rexroth valves, the frequency changes dependent on the command value and on the operating voltage.
Fault recognition [11]
The solenoid conductor is monitored for cable break as well as over-current of the output stage.
General
The amplifier modules are snapped onto top hat rails. The electrical connection is established via screw terminals. The modules are operated with 24 V direct voltage.
Power supply unit [1]
The amplifier modules have a power supply unit with making current limiter. This unit supplies all internally required positive and negative supply voltages. The making current limiter prevents high making current peaks.
Command value presetting
The internal command value signal is calculated from the total [3] of the external command value signal available at the differential input [2] and the zero point offset (zero point potentiometer “Zw”).
A positive command value results in a current increase in solenoid “b” and thus a flow in the valve from P to A and from B to T.
A negative command value results in a current increase in solenoid “a” and thus a flow in the valve from P to B and from A to T.
Enable function [10]
Using the enable function, the power output stages are enabled and the internal command value signal is forwarded to the ramp generator. The enable signal is indicated by an LED on the front plate. If enable is connected, the internal command value is changed (with any kind of command value presetting) by the set ramp time. Thus, a controlled valve does not open abruptly.
Ramp generator [4]
The ramp generator limits the incline of the control output. The downstream step functions and amplitude attenuators do not extend or shorten the ramp time.
Notices for setting and measurement of the ramp time:
Value at measuring socket “t ” |
U/V | 5 | 3 | 2 | 1 | 0.5 | 0.3 | 0.2 | 0.1 | 0.05 | 0.03 | 0.02 |
Current ramp time (±20 %) | t/ms | 20 | 33 | 50 | 100 | 200 | 333 | 500 | 1000 | 2000 | 3333 | 5000 |
- Component series 1X
- Analog, Modular design
- For valves:
4WRA 6…2X, 4WRA10…2X