This controller is designed to be used in applications where the pump is equipped with an electrical displacement control that can be varied to obtain the required operating speed range. The output signal to the pump displacement controller is bipolar, for reversing applications.
The hydrostatic drive controller is an extremely accurate bipolar linear current amplifier, when it is operated in the open loop mode, it is capable of maintaining the preset output within 1% as the input voltage, ambient temperature and load impedance are varied over the specified range.
The controller is supplied as a single, industrial grade modular circuit board assembly with a terminal block for external connections. The circuit board is solder masked and conformal coated. All models include a regulated bipolar reference supply as well as the devices required to set the pump null position, gain and maximum output. All of the user adjustment controls are multiple turn potentiometers that are clearly marked on the board. Operation is directly from the 115 VAC or 230 VAC power line or a bipolar 18 to 30 volt DC power supply. The output is capable of supplying a maximum of 200 ma. of current to the pump displacement control valve.
Optional features include linear acceleration and deceleration control as well as a built in dither generator module. The linear acceleration and deceleration option provides four adjustable ramp controls. The dither generator is supplied with controls to set both the amplitude and frequency of the dither signal to the servovalve coil. The controller is designed to accept a bipolar analog input to produce the required output speed and direction of rotation. This command signal can be obtained from the internal reference with a potentiometer or generated externally with suitable signal conditioning amplifiers. Bipolar input signals of 5 or 10 volts are standard. For unidirectional applications the controller will accept and follow a 4 to 20 ma. current input. For closed loop operation, a scaling circuit with adjustable gain has been included so that commonly available analog, velocity transducers can be interfaced with a minimum of external parts.
All of the external power and signal connections are made to a single barrier type terminal block supplied with #6-32 wire clamping screws. The various options and operating modes are selected with multiple position pin headers, thus the controller can be configured for a number of applications without the need to solder or remove any components.
Applications: Speed controller for variable displacement pumps and motors. General purpose servovalve amplifier for coils to 200 ma. Closed loop operation with suitable feedback.