VT-MSPA2-200-1X/V0/0

Formula to calculate the ramp times:

; t in ms, U in Volt at the measuring socket

Characteristic curve generator (4)

Using the adjustable characteristic curve generator, the step level for positive and negative signals can be adjusted separately to the hydraulic requirements. The actual development of the characteristic curve through the zero point is not stepped but linear.

Amplitude limiter (5)

The command value is limited to approx. ±110 % of the nominal range.

Current controller (6)

Der current is regulated based on the command value.

Power output stage (7)

The power output stage creates the clocked solenoid current for the proportional valve. The rated solenoid current is 1000 mA 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 is missing.

Clock generator (8)

The clock generator generates the clock frequency of the output stages.

f = 150 Hz … 400 Hz, adjustable using poti “f” (pre-set to 240 Hz)

Fault recognition (10)

The solenoid conductor is monitored for cable break as well as over-current of the output stage.

Command value inversion (11)

The command value created internally from the input signal and the zero point offset signal can be inverted by an external signal.

Monitoring and limitation of the solenoid current (12)

The monitoring and limitation of the solenoid current is performed by the VT-MUXA2-2 module.

General

The amplifier modules are snapped onto top hat rails according to EN 60715. 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.

Command value presetting

The internal command value signal is calculated from the external command value signal available at the differential input [2].

A positive command value results in a current increase in solenoid “b” and thus a flow in the valve from P → A and from B → T.

A negative command value results in a current increase in solenoid “a” and thus a flow in the valve from P → B and from A → 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 [3]

The ramp generator limits the incline of the control output. The downstream step functions do not extend or shorten the ramp time.

Table for setting and measurement of the ramp time: