ABB LTU-785 Termination Unit

ABB LTU-785 Termination Unit

Basic Introduction

ABB LTU - 785 Termination Unit is a terminal unit equipment launched by ABB. It is mainly used for the terminal connection processing of signals in industrial automation control systems, and is an important part to ensure the accurate transmission of signals and stable operation of the system.

Functional features

Signal terminal connection function

Multiple types of signal interfaces: It has multiple types of signal interfaces, including but not limited to analog signal interfaces (e.g. voltage and current interfaces) and digital signal interfaces (e.g. switching interfaces). This makes it possible to adapt to the signaling needs of different sensors and actuators. For example, in an automation plant, it is possible to connect the analog output signal of a temperature sensor (e.g. 4 - 20mA current signal) and the digital control signal of a motor start/stop.

High reliability of signal connections: Reliable connections are used to ensure that the signals are firmly connected and make good contact at the terminals. This helps to reduce the risk of interference and signal loss during signal transmission. For example, the interface may be equipped with high-quality terminals that provide a stable electrical connection and are resistant to vibration and corrosion, adapting to the complex conditions of industrial environments.

Signal Conditioning Functions

Signal Isolation and Filtering: The ability to isolate and filter the input signal. Signal isolation can prevent mutual interference between different signals, especially in the complex industrial electromagnetic environment, isolation measures can protect sensitive equipment from external interference. Meanwhile, the filtering function can remove the noise components in the signal and improve the quality of the signal. For example, for some weak analog signals, power ripple and high-frequency electromagnetic interference can be removed through filtering, making the signal purer for subsequent processing and transmission.

Signal conversion and matching: In some cases, signal conversion and matching operations can be performed. For example, digital signals of different level standards can be converted to match the input level requirements of the control system; or one type of analog signal (e.g., voltage signal) can be converted to another type (e.g., current signal) to meet the input requirements of the connected devices. This signal conversion and matching function enhances system compatibility and flexibility.

System Integration Convenience

Easy to install and configure: It is designed with ease of installation and configuration in mind. It usually adopts standard mounting methods, such as rail mounting, and can be easily installed in the control cabinet. In terms of configuration, the type of signal, interface function and other parameters can be determined through simple settings (e.g., by means of dip switches, jumpers, etc.), which reduces the complexity of the system integration process.

Good compatibility with other equipment: It is well compatible with other automation equipment from ABB as well as third-party industrial equipment. It can be seamlessly connected to various control systems as a signal terminal unit, and work with PLC (programmable logic controller), I/O modules, sensors, actuators and other equipment to realize the overall function of the system.

Technical Parameters

Interface parameters

Interface type and quantity: Interface types include analog interfaces (e.g. voltage interface: 0 - 10V, -10 - +10V; current interface: 4 - 20mA) and digital interfaces (e.g. switch input/output interface). The number of interfaces varies according to the specific model, generally there may be 4 - 8 analog interfaces and 8 - 16 digital interfaces to meet the signal connection requirements of different system sizes.

Electrical characteristics of the interfaces: The electrical characteristics of the different interfaces comply with the respective industry standards. For example, the input and output impedance of an analog voltage interface is within a certain standard range to ensure proper signal transmission, while the input and output levels of a digital interface are in accordance with TTL (Transistor Transistor Logic) or CMOS (Complementary Metal Oxide Semiconductor) standards, e.g., the input high level range may be from 2V - 5V, and the low level range from 0 - 0.8V.

Signal Processing Parameters

Isolation Voltage and Filtering Characteristics: Signal isolation voltages are typically capable of thousands of volts, e.g., between 1500V - 3000V, effectively isolating different signal circuits. For filtering function, it may have specific cut-off frequency, such as for high frequency noise filtering, the cut-off frequency may be between 1kHz - 10kHz, which can effectively filter out noise signals above this frequency range.

Signal conversion accuracy: In signal conversion, there are certain accuracy requirements. For example, for analog signal conversion (e.g. voltage - current conversion), the accuracy may reach between 0.1% - 1% of full scale to ensure that the converted signal can accurately meet the input requirements of the connected equipment.

Electrical parameters

Operating Voltage and Power Consumption: The operating voltage is typically in the 12V - 24V direct current (DC) range, which is compatible with power supplies commonly found in industrial sites and facilitates the use of standard industrial power supplies for power supply. Power consumption is typically low and may range from a few watts to more than a dozen watts under normal operating conditions, depending on the use of the interface and the complexity of the signal processing.