Tuesday, August 30, 2011

Generator Stator Rewedging

Generator Stator winding

Stator wedges

Stator core

Thin Layer Electrical Metal Steel

General info on stator core

The stator core has an internal diameter of 4630 mm and a length of 2250 mm. It is
built up from segmental laminations punched from high grade, cold reduced, electrical
sheet steel, which are held in the frame by dovetailed keybars. The laminations are
divided into 59 layers (packets) formed by narrow steel spacers which provide
ventilating ducts leading from the stator bore to the periphery of the core.

Stator winding

The stator winding is of the double layer lap type, each layer comprising 64
conductors (32 deep by 2 wide) and each conductor being 2.24 mm x 5.8 mm glass
laminate covered copper strip. The conductors are transposed within the slot length
to inhibit circulating currents between

Stator wedge plate layers.

The two layers (bars) are wound and packed into the open core slots. The top and
bottom bars are spaced apart by a separator and retained in the slots by wedges

Tuesday, August 23, 2011

Dry ice blasting on the stator

Dry ice blasting on the stator

Dry ice blasting is a form of abrasive blasting, where dry ice, the solid form of carbon dioxide, is accelerated in a pressurized air stream and directed at a surface in order to clean it. Dry ice blasting leaves no chemical residue as dry ice sublimates at room temperature.

Objective: To remove dirt and unwanted contaminants on the stator core. This process also removes the varnish stain on the stator core.

Working principles:

Dry ice blasting machine

Dry ice blasting is a form of abrasive blasting, where dry ice, the solid form of carbon dioxide, is accelerated in a pressurized air stream and directed at a surface in order to clean it. Dry ice blasting leaves no chemical residue as dry ice sublimates at room temperature.

Dry ice blasting involves propelling pellets at extremely high speeds. The actual dry ice pellets are quite soft, and very less dense. Upon impact, the pellet sublimates almost immediately, transferring minimal kinetic energy to the surface on impact and producing minimal abrasion.

Dry ice blasting - air compressor

The sublimation process absorbs a large volume of heat from the surface, producing shear stresses due to thermal shock. This is assumed to improve cleaning as the top layer of dirt or contaminant is expected to transfer more heat than the underlying substrate and flake off more easily. The efficiency and effectiveness of this process depends on the thermal conductivity of the substrate and contaminant.

Wednesday, August 17, 2011

Magnehelic Gauge. What Is A Magnehelic Gauge?

Mahnehelic Gauge
What Is A Magnehelic Gauge

A magnehelic pressure gauge is a device, similar to a manometer, used to measure positive, negative and differential pressures. These gauges are often used in the HVAC industry to measure pressure drop across air filters to determine when it is time for them to be changed.

Although magnehelic gauges are resistant to shock and vibration, they are extremely sensitive and accurate. Calibration is very easy due to the zero calibration screw located on the plastic cover. Although Dwyer makes gauges in about thirty different pressure ranges, the most common ranges are 0 to 0.5 in, w,g. (25 Pa), 0 to 1.0 in. w.g. (250 Pa), and 0 to 5.0 in. w. g. (1250 Pa). They consist of a die cast aluminum case and bezel with an acrylic cover. Magnehelic gauge accuracy is typically + or – 2%.

If you want to know more details, please go to the Magnehelic Gauge web.

Wednesday, August 10, 2011


The stator is the stationary part of a rotor system, found in an electric generator, electric motor and biological rotors.

Depending on the configuration of a spinning electromotive device the stator may act as the field magnet, interacting with the armature to create motion, or it may act as the armature, receiving its influence from moving field coils on the rotor.

The first DC generators (known as dynamos) and DC motors put the field coils on the stator, and the power generation or motive reaction coils on the rotor. This was necessary because a continuously moving power switch known as the commutator is needed to keep the field correctly aligned across the spinning rotor. The commutator must become larger and more robust as the current increases.

The stator of these devices may be either a permanent magnet or an electromagnet. Where the stator is an electromagnet, the coil which energizes it is known as the field coil or field winding.

An AC alternator is able to produce power across multiple high-current power generation coils connected in parallel, eliminating the need for the commutator. Placing the field coils on the rotor allows for an inexpensive slip ring mechanism to transfer high-voltage, low current power to the rotating field coil.

It consists of a steel frame enclosing a hollow cylindrical core (made up of laminations of silicon steel). The laminations are to reduce hysteresis and eddy current losses.

Wednesday, August 3, 2011

Bakun - Fast facts


The Bakun Hydroelectric Dam is the second highest concrete faced rockfill dam in the world.

Bakun dam is 207 metres high with a reservoir surface area of nearly 70,000 hectares, about the size of Singapore.

The main civil works began in 2002 by Malaysia-China Hydro Joint Venture.

A workforce of just over 3000 are on site at the peak of construction activity.

Experts, engineers, specialists and consultants worldwide are involved in this mega-project.

Upon completion, the Bakun Dam will generate 2400MW of clean electricity.

Bakun Dam is emission-free and has a 0% impact on global warming.

Monday, August 1, 2011

Activer Repeater for T24 Wireless Telemetry (T24-AR)

* Wireless Active Repeater module to increase or extend range and overall coverage
* Allows T24 telemetry transmission to span around obstacles such as buildings or walls, etc.
* IP65 rated NEMA4 protected
* Integrated PCB antenna
* Simple configuration via PC using base station & T24 Toolkit software
* Battery power supply or external power supply
* 1 year manufacturer’s warranty
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