Forms of Separation for Panel (PART-2)

(C) Form 3

  • This is more complicated but safer than Form 2.
  • In form 3a, each device is isolated in a compartment that protects it from the effects of any incidents that may occur on another Part / Switchgear.
  • Busbars and functional units are segregated. Functional units are also separated from each other in cubicles, and terminals are then separated from functional units, but they are not segregated from other functional units’ terminals.
  • Busbar and Switchgear: Bus bars are separated from the Switchgear units,
  • Busbar and Termination: Bus bars are not separated from any incoming or outgoing terminations.
  • Switchgear and Switchgear units: Switchgear units are separated from each other.
  • Switchgear and Termination: Switchgear units are separated from any incoming or outgoing termination.
  • Termination and Termination: Incoming and outgoing terminals are not separated from each other
  • This is further classified into 2 categories.

FORM 3A

  • External cabling terminals are not segregated from busbars.

FORM 3B

  • External cabling terminals are separated from busbars

FORM 3B TYPE 1

  • As from 3 but: Busbar separation is achieved by insulated coverings, e.g. PVC sleeving, wrapping or coating.
  • Terminals are therefore separated from the busbars, but not from each other.

FORM 3B TYPE 2

  • As form 3 but: Busbar separations is achieved by metallic or non-metallic rigid barriers or partitions.
  • Terminals are therefore separated from the busbars, but not from each other. 1

 Advantages:

  • The advantages include safety, ease of maintenance and reliability because it’s possible to isolate and perform maintenance on each starter without having to power down the whole switchboard.
  • Serious faults within a starter are also more likely to be contained within a cubicle meaning adjacent starters are unaffected and can operate normally.

Electrical Safety:

  • More reliable and safer than Form-2 due to separation between live parts (Busbar and Switchgear, Switchgear and Switchgear).

Cost:

  • All these advantages come at a cost as a Form 3 board is significantly bigger and more expensive than a Form 1 or 2 board.

Application:

  • Form 3 segregation is typically used for Big projects and larger operations that have a greater number of loads, motors and critical processes.
  • They are utilised when safety, reliability and limited downtime are crucial.

(D) Form 4

 This is the highest form rating, as specified by AS/NZS / IEC 61439.1.

  • Busbars are separated from functional units
  • Functional units are separated from each other
  • Terminations to functional units are separated from each other
  • Busbar and Switchgear: Bus bars are separated from the Switchgear units,
  • Busbar and Termination: Bus bars are separated from any incoming or outgoing terminations.
  • Switchgear and Switchgear units: Switchgear units are separated from each other.
  • Switchgear and Termination: Switchgear units are separated from any incoming or outgoing termination.
  • Termination and Termination: Incoming and outgoing terminals are separated from each other
  • This is further classified into 2 categories.

FORM 4A

  • External cabling terminals are within the same cubicle as the corresponding functional unit.

FORM 4B

  • The external cabling terminals are not in the same cubicle as the corresponding functional unit, and they are separated from the terminals of other functional units.

CLASSIFICATION OF FORM 4B

TYPE Busbar Separation Termination Location Cable Gland
FORM 4B TYPE-1 PVC sleeving, wrapping or coating. Termination is within the same compartment as the functional unit. Common Gland Plate
FORM 4B TYPE-2 Rigid Barriers Termination is within the same compartment as the functional unit. Common Gland Plate
FORM 4B TYPE-3 Rigid Barriers Termination is within the same compartment as the functional unit. Individual Gland Plate
FORM 4B TYPE-4 PVC sleeving, wrapping or coating. Terminals are external to the functional unit and separated by insulated coverings, e.g. PVC Boots Common Gland Plate
FORM 4B TYPE-5 Rigid Barriers Terminals are external to the functional unit and separated by insulated coverings, e.g. PVC Boots Common Gland Plate
FORM 4B TYPE-6 Rigid Barriers Terminals are external to the functional unit compartment and enclosed in their own compartment by means of rigid barriers or partitions Common Gland Plate
FORM 4B TYPE-7 Rigid Barriers Terminals are external to the functional unit compartment and enclosed in their own compartment by means of rigid barriers or partitions complete with integral glanding facility Individual Gland Plate

2

  • The major difference between Forms 3 and 4 is the separation of the terminals of each functional unit the terminals of other units.

Advantages:

  • The main advantage of this model is the ability to safely connect and disconnect outgoing cables while the rest of the switchboard remains in operation.
  • In Large Panel access is required for inspection, to reset an auxiliary function. If the point of isolation and termination are each in their own individual box this can be deemed safer than if all the devices and connections are behind a single door

Electrical Safety:

  • More reliable and safer than Form-4 due to separation between live parts (Busbar and Switchgear, Switchgear and Switchgear, Termination and Termination).
  • Due to internal segregation is to limit the effects on adjacent circuits if something goes wrong. An external fault should cause a device to trip but this must not have any effect on any other circuits.

Cost:

  • Form 4 board is significantly bigger and more expensive than a Form 3 board.

Applications:

  • used in hospitals or for critical industrial processes.

SUMAMRY OF FORM OF SEPERATION OF PANEL

SUMAMRY OF FORM OF SEPERATION OF PANEL

SEPERATION BETWEEN FORM-1 FORM-2 FORM-3 FORM-4
BUSBAR–SWITCHGEAR NO YES YES YES
BUSBAR–TERMIATION NO NO / YES YES YES
SWITCHGEAR—SWITCHGEAR. NO NO YES YES
SWITCHGEAR–TERMIANTION NO NO NO YES
TERMIANATION–TERMIANTION NO NO NO YES

About Jignesh.Parmar (B.E,Mtech,MIE,FIE,CEng)
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE) and CEng,India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

2 Responses to Forms of Separation for Panel (PART-2)

  1. Dr. Muhammad Mohsin Ansari says:

    Thanks……Jignesh Parmar

  2. Manish Kumar N.Sinha says:

    You are invited for expert talk to our electrical engineering students.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: