Difference between 2-wire, 3-wire, and 4-wire signal transmitter connections

4–20mA sensor transmitters are very common in industries to measure physical parameters such as pressure, temperature, flow, etc. Based on how they are connected to the process control and automation systems, they are classified into 2-wire, 3-wire, and 4-wire signal transmitters. This article will help you understand the underlying concepts and the difference between 2-wire, … Read more

The Concepts of a 4-20mA current Loop

4-20mA Current loops are widely used to transmit process variable data such as temperature, pressure, flow rate, level, consistency, speed, etc between the process controllers and the field devices. Transmitters convert these process signals to 4-20mA DC for the purpose of transmitting the signal. This signal can be transmitted to a long distance with little … Read more

Rogowski Coils

A Rogowski coil is an electrical transducer, that functions similar to a current transformer and is used in a variety of applications to measure alternating current (AC). It is named in honor of German physicist Walter Rogowski for his contributions to the field of electronics. Construction-wise they are a bit different from the normal current … Read more

Instrument transformers – Definition, types and connection

What is an instrument transformer? Instrument transformers are current and voltage transformation devices that are used to step down the transmission and distribution line voltages and currents to levels that can safely operate measuring instruments, protection devices and control relays by isolating it from the supply voltages. The above diagram shows the basic usage of … Read more

Potential transformers | Voltage transformers (PT)

Potential transformers (PT) or voltage transformers are instrument transformers used for voltage measurements. They are connected in parallel to the line and operates under the same principle of power transformers. They cannot be used used to supply raw power to the loads. They have an accurate voltage ratio and phase relationship between primary and secondary … Read more

Current transformers (CT)- working, types and connection

What is a current transformer? A current transformer is a type of instrument, used to measure or sense large alternating currents by scaling it to a smaller, safer and measurable value. It transforms the primary current to a proportional secondary value in terms of magnitude and phase. Current transformers are available in various sizes and … Read more

Difference between NPN and PNP transistors | NPN vs PNP Transistor

The bipolar junction transistors exist as NPN and PNP types. This article intents to help you understand the difference between these two types and how to use them in a circuit. Also, this will be helpful to automation engineers and instrumentation engineers in understanding 3 wire sensor connections. Transistors are made by combining two types … Read more

Types of Proximity sensors and their applications

Proximity sensors are used to detect the presence of an object without any direct contact. It is used as an alternative to the limit switches. There are various types of proximity sensors available in the market. Their invention led to a revolution in the field of industrial automation and robotics. Proximity switches were developed by Wilfried … Read more