The purpose of the DIN module electronics range of products is to provide standard building blocks for creating customized control systems for open and closed-loop control. This approach gives us a set of products that are built in quantity with full customer support documentation for installing, commissioning, and maintaining the resulting solution. For this reason it is preferable to aim for standard catalog modules.
However there are instances where small changes will give major benefits in terms of cost and performance. Generally, those changes will be within the available functionality of the module and be reflected in the dash number at the end of the model code.
Our standard PI Servo Amplifier is the 'parent' to customized models with variations such as:
- Additional environmental protection for H(2)S exposure in geothermal power stations. This is achieved with conformal coating and reloading of some devices where material corrosion is a potential problem.
- Inclusion of 4-20mA output only for turbine applications.
Typical changes to the 'parent ' product involve environmental protection, change of resistors, additional loading to the available capacity of the existing PCB layout. Generally, we are taking a standard product from stock and making minor changes.
Moog can provide many such changes within a very short delivery period at similar prices to the 'parent' product. A 10% premium is typical for small changes. If quantities are sufficient, it may be possible to justify a new product development.
The Mobile Servo Amplifier has been designed for a wider range of customization with specific building blocks allocated. Its designation as "Mobile" relates to the ruggedized power supply that will operate from the very noisy automotive environment and obviously, it is also suited to 24 volt unregulated industrial supplies. This closed-loop servo amplifier has provisions for easy loading of options such as:
- Frequency to voltage converter for velocity feedback.
- Non-linear function.
- Dual gain amplifier for high speed, high accuracy positioning.
A recent application used a DIN module to control the vertical movement of a lock crane boom. Located on the River Murray in South Australia is a series of locks for flood control. Concrete beams are lowered into slots to vary the height of underwater barriers.
The task of the control system is to simplify the control of the excavator boom to achieve an accurate horizontal movement of the beams as they are moved into position.
A closed-loop position control with feedback from a pendulum sensor has been applied with the following components:
- Servovalve with “outdoor” environment protection.
- Customized Mobile Servo Amplifier
- Pendulum level sensor
The Mobile Servo Amplifier was chosen due to its suitability to operate directly from standard “automotive” style power supplies without the risk of electrical damage and the ease of adding custom control requirements. DIN style packaging meant that a compact and reliable installation could be achieved in this relatively harsh environment.
Of course, there is a limit to how far we can go with analog electronics. For complex control with digital interfacing it is preferable to use digital solutions such as the Moog Servo Controller (MSC) or Digital Interface Valve (DIV), that offer complete flexibility with respect to control strategies. However, many simple control systems will be successfully implemented with the standard Moog DIN modules or from simple customization of these analog electronics.