What is Grounding System | Grounding types-single point,multi point,hybrid

This page mentions grounding system basics,purpose of grounding,types of grounding viz. single point grounding,multi point grounding and hybrid grounding.It mentions different types of grounding methods and materials used in test and measurement equipments.

Definition: The grounding can be defined as connection between an electrical circuit or equipment and earth or to some conducting body which serves in place of earth. The system or equipment which gets grounded is said to be grounding system.

In other words, grounding is nothing but connection to earth or to a conductor which serves as earth. The connection between circuit and its 0 volt reference can also be considered as grounding.

Purpose of grounding: Following are the reasons of doing grounding.
• To prevent shock hazard which exists in high voltage distribution system.
• Protection against lightning and ESD hazards
• Protection against EMI (electromagnetic interference)
• Power fault clear out

Grounding system types-single point grounding, multi point grounding, hybrid grounding

Grounding system types, single point grounding, multi point grounding, hybrid grounding

The figure-1 depicts types of grounding system as described below.
Single point grounding: Here each of the subsystems or modules have their own separate ground. All the individual grounds are connected to a single system ground point using simple wires. This type is suitable for low frequency analog circuits.
Multi point grounding: In this type of grounding, each subsystem or module is bonded as directly as possible to common low impedance equi-potential ground plane. This type is suitable at high frequency digital circuits, as at such frequencies metal sheets offer less impedance.
Hybrid grounding: The combination of single point grounding and multi point grounding refers to hybrid grounding. Here grounding points of both the systems are combined to a common point as shown. This type of grounding is used for mixed signal circuit design involving both analog and digital circuits and having both low frequency and high frequency parts.

Following table mentions various grounding methods and materials used in test and measurement equipments. This is also known as grounding hierarchy. It is used for typical installation of equipments.

Equipment type Grounding method/material
Low Level, Low Frequency simple wire can be used for grounding. Method is used upto few KHz.
Low Level, High Frequency This method is used upto tens of MHz, mesh is used for grounding as it provides low inductance.
High Level, High Frequency This method is used upto hundreds of MHz, grouding is done using flat metal strips to ground plane.

The ground hierarchy include grounds for cables as well as Transformer Shields, grounds for DC return, grounds for lightning and AC power safety.

What is difference between or comparison between

Following links mention difference or comparison between various equipments:
comparison between VSG and VSA
DIfference between SNA ans VNA
Oscilloscope Bandwidth versus Rise time
Oscilloscope vs Logic Analyzer
Difference between Oscillscope types
Comparison between spectrum and network analyzer