25KV ISOLATOR FOR OHE

Isolator

??These equipment is used to isolate different elementary sections manually. This can be of hand operated type or motorized one. Mostly it is used in making electrical separation between main lines and loop lines and for separating machine sidings, hot axle sidings etc. from main lines.

??Types of isolator

??????A) Single pole isolator

??????B) Double pole isolator

25 kV AC Single Pole Isolator (SP) & Double Pole Isolator?(DP)

Type??????????????????????:?Manually operated, horizontally mounted on pole, vertical break type and suitable for outdoor.

?Number of phases?:?One

?Number of poles???: ??????One or two (as specified by the purchaser)

Isolating distance???: 500 mm (min.) (In air)

Rated current?????????:

Type- I????????????????????: ????????1250 A?( Isolator used at Sectioning and?paralleling post & Sub-sectioning and paralleling post).

Type – II????????????????: ?????????1600 A ( Isolator used at Feeding post & Traction substation)

Type – II????????????????: ?????????3150 A ( Traction substation when load on OHE is More I.e. system has three line to feed in open section)

?Rated frequency???:??50 Hz. +/-3%

What is Isolator?

It is a manually operated switch capable of isolating the smallest section of OHE network either for attending faults or for maintenance.

Manually operated isolator switches are provided at different points on the main line to sectionalize the OHE into elementary sections and at large yards to isolate different elementary sections for maintenance of the OHE

The operating handle of every isolator switch?shall always be kept locked either in the open or closed position.

why Isolator is used?

Operation of Isolator for fault isolation or maintenance.

Isolator Operation

An isolator switch is not meant for breaking a current, but only to break a circuit when no current is passing through it. If an attempt is made to open a switch when It is actually carrying current, severe arcing will occur at the switch contacts and may result in serious consequences including danger to the operator.

Isolator switches on the main line may only be opened provided the corresponding sub-sector is first made dead by TPC.

The person operating the isolator switch shall not open it, unless specifically asked to do so by TPC by a clear message supported by a private number or after receipt of a separate permit-to-work for the section which includes the elementary sections on either the isolator switch.

TPC shall ensure that the sub-sector is dead before he orders opening of an Isolator switch in it.

Isolator switches, however, can be closed by a duly authorised person even if the adjacent lnterruptors are closed (i.e. on load) provided the closure is made swiftly in one motion. It is imperative that once the fixed and moving contacts have met, the contacts are not separated.

Earth Contact Assembly

The isolator shall be such that it is possible to incorporate an additional pair of contacts so as to effectively earth the fixed contact of the isolator in open position

Arcing Horn

The isolator shall be provided with arcing horns which shall be of bright steel

The arcing horns shall make contact before the main contacts close and break contact.

Major component

Isolator assembly

Solid core post insulator assembly

Operating rod insulator

Post insulator jumper clamp

Integral lock

Earth contact assembly

Isolator sps

Isolator Testing Details

Insulation Resistance Testing

Contact Resistance Testing

Timing Testing for Close/Open

Motor Resistance Testing (if Motorized)

General Checking & Visual Inspection'

Isolator Operational Testing with Interlock (Local / Remote,Electrical & Mechanical).