STG

RRA Diode

Check with multimeter 

Value between 300 to 450 only

STG Cleaning

1. Cleaning with Dry Ice

STG

Bearing Test

Damaged or not 

1. Thickness 

2. Cracking with DP test

Bimetallic Bearing - Bearing metal 0.4mm , rest other metal SS

1. Bearing metal 

0.4mm thickness

While removing checking by lead wires

STG - 0.278mm

2. 

DP Test

Die Penetrating Test

1. Cleaner

2. Penetrant 10min apply then clean with cloth

3. Developer - white flim with purple patches where damaged area

% Impedance Transformer

 What is % impedance of transformer?

Friday, September 11, 2015

The % impedance is formally referred to as impedance voltage. It is the supply voltage, expressed as a % of rated voltage, that is required to circulate rated current through the transformer.

It is measured in the factory by a short circuit test at rated frequency. With the low-voltage winding shorted, the supply voltage to the high-voltage winding is increased until rated current flows in the transformer. The supply voltage magnitude that results in rated current is then referred to as the impedance voltage. When it is divided by the rated voltage of the transformer, it becomes the %- impedance voltage, or more commonly, the %-impedance.

For example, if you have a transformer with a positive sequence impedance of 8% stamped on the nameplate, this means that 8% of the rated winding voltage is required to produce rated transformer current. If the high-voltage winding is rated at 220 kV, then 0.08*220 kV = 17.6 kV is required to produce rated full-load current when the low-voltage winding is shorted. This test is typically conducted under normal cooling conditions (i.e., natural air and oil; no forced air fans or forced oil pump cooling).

The positive sequence impedance is determined by a three-phase short circuit test; and the zero sequence impedance is determined by a single-phase short circuit test.

It is also a good indicator of how the transformer will fit into a soft or stiff system, in terms of its fault level and voltage regulation aspects. A system that is weak (high impedance) will be vulnerable to voltage regulation problems and installing a high %Z transformer will make that situation worse. We used to stipulate low %Z transformers (2-3%) at the remote ends of long distribution systems, otherwise starting large motors was problematic (volt drop). High %Z transformers are good to reduce fault levels and associated PSCC, to within the design ratings of the system switchgear etc, on very stiff systems with low impedance and high PSCC levels.

Capacitor

 LT Power Capacitors for a wide range of applications from direct compensation to automatic PF correction panels. We have on offer MPP,APP and MDXL capacitors in both cylindrical and box type construction. Due to the inherant advantages of oil impreganted capacitors over dry type and gas filled ones due to higher ambinet tempeatures in the Indian subcontinent our offered capacitors offer the highest resliable for even the most critical of applications . Our group firms combined are the largest suppliers of AC film capacitors in Eastern India.

We offer the following type of capacitors in different constructions as detailed below :

• APP (Al polypropylene type) type
• MPP (Metalized polypropylene type
• MDXL(Mixed Di-electric) type

TECHNICAL SPECIFICATIONS
Parameters	MPP	APP
Type	MKP Cylindrical / MS Box	Range 50 to 500 KVAr
Casing	Casing Steel Sheet	Casing Steel Sheet
Rated Voltage	220V – 690V, other voltage ratings available on request	415/440/480/525/690/850/1000 V 3 Phase (1 Ph capacitors available on request)
Protection	Dry Type, Self-Healing, Internal Over Pressure Disconnector	Protection Internal fuse / HRC fuse
Capacitors	Wide Range-Standard Duty, Heavy Duty & Super Heavy Duty	Capacitors APP type Ultra Heavy Duty Series used are rated at 415/440V, 50/60Hz as per network voltage.
Impregnation	Non PCB, Biodegradable Natural Oil, High Viscosity Resin	Impregnation Non PCB, Biodegradable Oil
Over Voltage	Un +10% (12h/24h), Un +15% (30m/25h), Un +20% (5m/24h), Un +30% (1m/25h)	Un +10% (12h/24h), Un +15% (30m/25h), Un +20% (5m/24h), Un +30% (1m/25h)
Standary Duty Capacitors	Rated Reactive Power- 0.25-50 KVAR Single Unit	Discharge Resistors fitted, Standard discharge time 60 seconds, Other discharge times on request
	Over Current - 1.5 In
	Inrush Current - 200 In
	Life Expectancy - >1,00,000 Operating Hours
	No. of Annual Switching Operations - 5,000
Heavy Duty Capacitors	Rated Reactive Power- 5-50 KVAR Single Unit
	Over Current - 2.0 In
	Inrush Current - 300 In
	Life Expectancy - >1,50,000 Operating Hours
	No. of Annual Switching Operations - 10,000
Super Duty Capacitors	Rated Reactive Power- 5-37.5 KVAR Single Unit
	Over Current - 2.7 In
	Inrush Current - 400 In
	Life Expectancy - >2,50,000 Operating Hours
	No. of Annual Switching Operations - 20,000

MPP	APP
PRODUCT FEATURES	PRODUCT FEATURES
TIBCON make PFC Capacitors are made in accordance with Metalized Polypropylene technology with built in self healing properties. The elements are wound on fully automatic numerically controlled winding machine. The elements are housed in cylindrical shaped aluminium case within built explosion proof safety device and imreganted with dry resign( for standard duty capacitors) and non-PCB oil( for heavy/super heavy duty capacitors). For box type capacitor banks, multiple single phase cells are delta connected and housed in powder coated sheet steel enclosured. Hence our construction of box type oil filled capacitors is also called modular construction. The range of PFC Capacitors is three different types - Standard Duty (220/400/415/440V), Heavy Duty (415/440/480/525/690V) and Super Heavy Duty (415/440/480/525/690V). These capacitors are manufactured by using varied thickness of dielectric material with heavy edge metallization.	LV Power Capacitors Bank is intended for the improvement of Power Factor in low voltage power networks. BITCON Capacitor bank comes with Robust & Highly reliable capacitor performance. These are the simplest and most economical means of increasing the capacity of any power system, minimizing energy losses and correcting load power factor. In addition, internal fuse to each element is possible for better safety, quality can be enhanced.
PRODUCT BENEFITS	PRODUCT BENEFITS
Compact Cylindrical Construction of capacitor.	Flickering
3 Phase - Delta Connection	High purity (>99%) Aluminium Foil used asElectrode for high current inrush.
Non - PCB Oil Encapsulation	Reducing power losses generated in the transformers and conductors of the installation.
High Temperature Withstanding Capacity	Guaranteed output for a longer period i.e.10-15 years.
Self-Healing Properties	Basic elements are vacuum impregnated with NPCB PXE oil
Explosion Proof Design Safe-Touch, Shock-Proof Terminal	Saves energy by reduced max. Demand, PF bonus & saving in Transformer losses
Longer Life Expectancy	Built-in network analyser, measuring all network parameter including harmonics
Eco-Friendly	Protection, durability, and safety you can trust.
Wide Range-Standard Duty, Heavy Duty& Super Heavy Duty

Critical Motor Testing

1. Avoid IR Test - Affects life of Motor

2. Motor Signature Analysis -

 Bearing

Rotor condtn

Winding condition

3. Polarization Index - Ratio of 10min IR/ 1 min IR

INGRESS PROTECTION / IP RATINGS

Ingress Protection ratings or IP ratings are defined by international standard IEC 60529, which classifies the degrees of protection provided against the intrusion of solid objects (which includes body parts like hands and fingers), dust, accidental contact, and water in electrical enclosures. The IP Rating provides a clearer meaning rather than vague marketing terms such as waterproof or water resistant.

IP Rating for solid objects.

The numbers indicate conformity with the conditions shown below with the first digit indicating the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects.

Solid foreign objects can be anything from fingers (ouch!) to tools to dust and anything in between. Knowing what degree of protection the housing provides should be a key part of health and safety planning both for existing equipment and new purchases.

For further information on IP Rating is available using the following links:

• IEC 60529 – “Degrees of protection provided by enclosures (IP Code)”
• IEC Standards
• NEMA Enclosure Ratings
• Wikipedia Article – “IP Code“