Standard Types of 11KV MetalClad Switchgear according to WAPDA Specification P-44:96

1. Incoming Panel for connecting the 11KV switchboard to the Power Transformer.
2. Outgoing Panel for connecting supply to 11KV feeder. 
3. Bus Coupler Panel for connecting two 11KV sections in Grid stations where two Power transformers are installed and for Grid station auxiliary supply. 
4. Industrial Panel for giving 11KV supply to individual consumers.
5. Ring main Panel for giving 11KV supply to individual consumers fed from two different feeders.
6. Consumer Panels for giving connection/ 11KV supply to an individual consumer from the Grid stations through an express or dedicated 11KV feeder 

Standardization of Panels according to WAPDA Specification P-44:96

1. Panels manufactured by different manufacturers shall be interchangeable.
2. The following components shall be standardized:
1. CTs & PTs
2. Supporting Insulators
3. Bus Bars
4. Meters
3. At every Panel, the incoming AC/DC circuits shall be connected to the terminal block of the panel from where the supply shall further be distributed through miniature circuit breakers of appropriate rating & characteristics. 

Transformer Efficency:

Transformer is a static device which transfers the power from one circuit to other through electromagnetic induction. In electrical transformer as there are no moving parts,

 1. no friction and
 2. windage losses occur

 and other losses in transformer are less as magnetic path of a transformer is a closed loop (no air gap exist like induction motor between two circuits). Losses in the transformer are very less compared to any other rotating machine, hence efficiency of transformers will be very high. Efficiency will be of the order of 95% to 98%.

Transformer Taps:

Taps are provided on some transformers on the high voltage winding to correct for high or low voltage conditions, and still deliver full rated output voltages at the secondary terminals. Standard tap arrangements are at two-and-one-half and five percent of the rated primary voltage for both high and low voltage conditions.

Transformer & Its Working:

"A transformer is an electrical apparatus designed to convert alternating current from one voltage to another" 

 

• It can be designed to “step up” or “step down” voltages and works on the magnetic induction principle.
• A transformer has no moving parts and is a completely static solid state device, which insures, under normal operating conditions, a long and trouble-free life. 
• Construction of transformer is very simple, two or more coils of insulated wire wound on a laminated steel or iron core. When voltage is introduced to one coil, called the primary winding, it magnetizes the iron core. A voltage is then induced in the other coil, called the secondary winding or output coil. The change of voltage (or voltage ratio) between the primary and secondary depends on the turns ratio of the two coils.

General Requirements for 11KV MetalClad Switchgear according to WAPDA Specification P-44:96

• The Switchgear shall be designed for indoor use only.
• each panel will be comprise of a draw-out type circuit breaker and shall be capable of being connected to a switch board on either side.
• All the associated equipment shall be self contained and self supporting.
• All live parts such as circuit breakers, bus bars, voltage transformers, current transformers etc. shall be enclosed within grounded metal compartments separated by grounded metal barriers. 
• Automatic shutters shall be provided to prevent exposure of live parts.
• Busbars & their connections shall be insulated.
• Mechanical interlocks shall be provided so as to ensure safe operation of the switchgear in the correct sequence.  
• All the secondary circuits, wiring & instruments etc., shall as far as possible be isolated by grounded metal barriers from all primary circuit elements with the exception of short lengths of wire such as at instrument transformer terminals.
• Switchgears shall be designed & manufactured to secure safety during operation, inspection, cleaning and maintenance & shall be so arranged as to minimize the risk of fire arising or spreading.

Service Conditions for 11KV MetalClad Switchgear according to WAPDA Specification P-44:96

Ambient Temperature:
Maximum Temperature    50 deg. C
Maximum Mean over an hour    45 deg. C
Mean in any year   30 deg. C
Minimum Temperature - 10 deg. C

Relative Humidity:
Relative Humidity may range upto 100%.

Altitude:
Installation upto 1000m above sea level.

Supply System:
The Switchgear shall be suitable for installation in 11KV three phase AC supply system of the following characteristics:

Nominal Voltage 11KV
Rated Voltage 12KV 
Frequency  50Hz

Metalcald Switchgear WAPDA specification P-44:96

• This specification has been prepared by Design Department , Power Wing, WAPDA.
• These specifications was first introduced in August 1968.
• Its revised editions were issued in 1979,1985 & 1987.
• These specifications applies to 11KV A.C three phase metal clad switchgear for indoor application.
• the switchgear covered by this specification comprises of SF6 & Vacuum Type Circuit Breakers. 

• Reference Standards

The switchgear, including the operating devices and the auxiliary equipment which form an integral part of it,shall be designed, manufactured and tested in accordance with the following International Electro-technical Commission (IEC) Publications:

• IEC -    56                 HV AC Circuit Breakers 
• IEC -  298                 AC metal enclosed Switchgear & Control
• IEC -  694                 HV Switchgear & Control Gear COmmon Clauses
• IEC - 185                  Current Transformer
• IEC - 186                  Voltage Transformer
• IEC - 265-1               HV Switches
• IEC -   51-1               Electrical Measuring Instruments & their Accessories

• IEC -  51-2                 Same as above
• IEC -  51-3                 Same as above
• IEC -  51-5                 Same as above
• IEC -  51-8                 Same as above
• IEC -  468                  Measurement of Resistivity of Metallic materials

Electrical Advice/ Services

 ZGL Pakistan

You need any electrical advice/service don't worry, just call, as ZGL Offers complete range of Manufacturing & Services round the clock

Transformers:

• Manufacturing up to 5000KVA(Any Type, Any Quantity)
• Repairing / Maintenance & Overhauling (Power/ Distribution)
• Sale, Purchase, Exchange & Renting etc.
• Complete range parts accessories, sale & services.
• Oil Leakage Removing all types.
• Oil Dielectric & Chemical Testing.
• Oil Dehydration/Filtration & De-gasification.
• Oil Dehydration plants capacity.

1.  2 x 1200~1500 liters/hour for Distribution Transformers.
2.  1 x 10000~12000 liters/hour for Grid & Power Transformers.

• Inspection & Testing of 11KV Distribution & 132KV Power Grid Transformers.

Switchgear Panels

• Manufacturing of HV ,MV & LV (SF6 / VCB / ACB / PFI / PDB / LDB)
• HT / LT substation complete range panels etc.
• Switchgear panels Repairing / Maintenance & Overhauling.
• 11KV/132KV Panels Sale, Purchase & Services etc.
• 11KV/132KV complete range parts/accessories, sale & services.
• Inspection, Testing & Calibration of Power & Distribution Electrical Equipment installed at 11KV & 132KV stations.
• Calibration of Protection Relays & Energy Meters.
• Earthing Testing.

Cables / Accessories & Services

• 11KV XLPE Cables.
• Termination Kits, Joint Kits & Accessories etc.
• Cable Hi-Top Testing ~40KV DC by German Tester.

Annual Electrical Inspection & Test Reports

• Annual Inspection of electrical installation & test report.

(Approved Electrical contractor in Category 'A' for Unlimited Load) 

MV Switchgear Type Tests

1. 95KV Impulse Test. (HV & SC Lab Rawat)

2. Temperature Rise Test.

3. Measurement of resistance of main Circuit.

4. Verification of making and breaking capacities.

5. Mechanical Operation Test.

6. Measurement of Leakage Currents.

7. Test of arcing due to internal faults.

8. Short Circuit Life Test.

ZGL Transformers & Switchgears, Pakistan

Company Overview:

• MANUFACTURER
• STOCKISTS 
• BUYING
• SELLING
• RENTING
• REPAIRING
• TESTING
• CALIBRATION

Description:

Company got recognition from 

• FESCO / WAPDA
• IEEE-P
• ISO 9001
• PEC

for the Manufacturing, Inspection & Testing of Transformers & Switchgears.

• Company is also licensed from C.E. Power, Govt. of Punjab for issuance of Electrical Contractors License in category ‘A’ for Industrial Electrical Inspection & Testing activities etc.