if you hang from a busbar with any part of your body touching nothing will happen. But you touch busbar while standing the ground, there is a contact between the line to ground and there will create a L-G fault. you will receive a heavy electric shock before the CB trip and it is enough to cause death.

Busbars (also referred to as bus bar) are fascinating feats of engineering making complex power distribution simpler, more affordable and flexible. The main purpose of busbars is to conduct a substantial current of electricity and are typically housed inside switchgear, panel boards or busways.

In electric power distribution, a busbar (also bus bar) is a metallic strip or bar, typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution.

In power-intensive electrical applications, a busbar (often also spelled bus bar or bussbar) is a critical element for conducting significant current levels between functions within the assembly.

The IEEE states a busbar should be rated at the highest amperage passing through any section of the busbar, with a maximum of a 50° C rise in temperature from an ambient temperature of 50° C. This rating method avoids excess terminal temperature at the wire termination.

Busbar protection is a protection scheme meant to protect the busbar from electrical fault. The main purpose of this busbar is to increase the reliability of power system by maintain the evacuation of power in case of tripping of any feeder due to fault.

Busbar protection schemes

• System protection used to cover busbars.
• Frame-Earth Protection. Single-Busbar Frame-Earth Protection. Frame-Earth Protection (Sectioned Busbars)
• Differential protection for busbars. High Impedance Differential Protection.
• Reverse blocking / interlocking protection.

It is used to convert the bus voltage to a safer lower value for metering and indication . It provides both isolation and scaling. A PT is an instrument transformer. It is used to convert the bus voltage to a safer lower value for metering and indication .

Line pt means to measure incoming line voltage. Thebus pt means measure. The bus needs to be protected under the bus’s voltage.

Applications of Voltage Transformers On other hand PTs used for protection called as protection voltage transformers. In some cases PTs are used for both metering and protection purposes, in such cases, one secondary winding is connected to metering and other secondary winding is used for protection.

A Potential Transformer (PT), or Voltage Transformer (VT) is an Instrument Transformer used for measuring voltage.

PT needs to be connected in parallel because we need to measure the voltage. These are similar to voltmeter and Ammeter.

CT and PT are used where large quantities of currents and voltages are used. The job of CT and PT is to reduce high current and high voltage to a parameter. With the help of this parameter, we can measure the current flowing at high volume and voltage.

The load, or burden, in a CT metering circuit is the (largely resistive) impedance connected to the secondary winding. This means a CT with a burden rating of B-0.2 can tolerate up to 0.2 Ohms of impedance in the metering circuit before its output current is no longer a fixed ratio to the primary current.

Difference Between Current Transformer (CT) & Potential Transformer (PT) One of the major difference between them is that the current transformer converts the high value of current into low value whereas the potential or voltage transformer converts the high value of voltages into low voltage.

Also Potential transformers are higher in cost as compare with the current transformer. The cost will be reduced as the burden increases, instead of that if we go for New potential transformer for feature loads we have to install additional PTs.

Burden for Metering type CT = Total Burden of Meters (Digital/Analog Ammeter, Voltmeter, Power Meter, MFM, Transducer) which are in series with CT + The total VA of the Cables connecting CT and the Meters. Cable VA = (2L x R x I^2). Cable VA= 5^2 x 0.02 x 2 x 2=2VA .

Definition: 1) The ratio of primary amps divided by secondary amps. 2) The current ratio provided by the windings of the CT. For example, a CT that is rated to carry 200 Amps in the primary and 5 Amps in the secondary, would have a CT ratio of 200 to 5 or 40:1.

Generally current transformer is called as CT. Otherwise (polarity reversed), the devices starts malfunctioning, i.e energy meter shows negative readings, relay may read negative current hence relay may activate the trip circuit, reverse power relay activation is alternator or generator circuits etc.