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. 

 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

• 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