© Delba Electrical, Springs, Gauteng, South Africa : Design
Total Electric Motor Solutions

What Is Vacuum Pressure Impregnation?

Vacuum Pressure Impregnation (VPI) is a process that uses vacuum and pressure to seal porous

materials with varnish or resin. The process is used primarily for high-voltage motors and

generators to fill gaps in materials to create a void free insulation in various devices.

Industrial electromechanical equipment is designed for durability to provide reliable function and

increased longevity, but age, temperature, and environmental factors can degrade porous metals

over time. The process of impregnation seals porous materials with varnish or resin, improving

the function and longevity of equipment.

Delba Electrical. Electric Motor Sales, Rewinding, Repairs and Maintenance, Gauteng.
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Services

Vacuum Pressure Impregnation Plant - VPI Plant

View Video View Video Featuring Curing oven from Italy and VPI plant from South Africa Resin Storage Tank Stator being lowered for VPI process Stator on its way to start an impregnation cycle Stator on its way to start an impregnation cycle

Global Vacuum Pressure Impregnation (VPI) Process

Global Vacuum Pressure Impregnation (VPI) is a process in which ‘green’ coils (dry, porous) are placed in a stator, and then the whole stator is processed. The process involves a stator (at room temperature or slightly heated) being placed in a ‘dry’ tank and a vacuum (as close to pure vacuum as possible) being applied for a designated period of time. The tank is then quickly filled and a pressure applied, usually about 6 bar, and the stator is allowed to ‘pressure soak’ for another designated period of time. At the end of the cycle the resin is drained, pressure is ‘blown off’ and the stator is baked, curing the resin. The vacuum cycle causes most air and moisture to escape from the coils which also creates a ‘sponge’ as some of the air is still trapped, but expanded. When the resin is in the tank and the pressure is applied, any remaining air shrinks and draws the resin through the tapes and into the coil. High performance vacuum pumps, controls, sensors, filters, dryers, and refrigeration systems are usually included in modern systems. For more reliable and homogeneous results, state of the art VPI plants are often completely automated providing a stable environment for the impregnation process to take place, moreover modern systems can be additionally equipped with viscosity measuring devices that keep continuous track of the resin viscosity at any given temperature thus eliminating the need for regular resin controls. Most VPI system manufacturers and resin suppliers provide an estimated time chart for each part of the cycle based upon averages and long term experience. There are several ways of determining penetration of epoxy resins through the global VPI cycle, however the most direct, efficient and reliable one is to perform capacitance measurements during the VPI cycle and to monitor the resulting curve, directly proportional to the degree of “saturation” of the porous insulating wall which also allows comparison when similar stators are processed. The capacitance monitoring system on the global VPI is an excellent method for maximizing confidence in completed stators.

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Testing Services Provided Testing Services Provided
Delba Electrical. Electric Motor Sales, Rewinding, Repairs and Maintenance, Gauteng
Total Electric Motor Solutions
© Delba Electrical, Springs, Gauteng, South Africa : Design

What Is Vacuum Pressure Impregnation?

Vacuum Pressure Impregnation (VPI) is a

process that uses vacuum and pressure to

seal porous materials with varnish or resin.

The process is used primarily for high-

voltage motors and generators to fill gaps in

materials to create a void free insulation in

various devices.

Industrial electromechanical equipment is

designed for durability to provide reliable

function and increased longevity, but age,

temperature, and environmental factors can

degrade porous metals over time. The

process of impregnation seals porous

materials with varnish or resin, improving

the function and longevity of equipment.

Services

Vacuum Pressure Impregnation Plant -

VPI Plant

Medium Voltage / High Voltage

Machine Repairs

Details below of all the different facilities Delba

Electrical has in place to ensure we can do any

type of repairs on Medium Voltage and High

Voltage machines.

Low Voltage Machine Repairs

Details below of all the different facilities Delba

Electrical has in place to ensure we can do any

type of repairs on Low Voltage machines.

DC Machine Repairs

Details below of all the different facilities Delba

Electrical has in place to ensure we can do any

type of repairs on DC Machines.

Vibrator Motors, Fans and Pumps

Traditionally vibrator motors operate in the field under very onerous conditions and are subject to abuse. DELBA has a dedicated workshop set up specifically for the repair of all of the available types of these machines with the purpose of returning them to their OEM condition. In order to achieve this, special attention is given to the type of bearings used, the grease used and the tolerances of the bearing housings. Additionally, all vibrator motors are thoroughly tested, including load testing prior to dispatch.

Testing Services Provided

Tan Delta / Capacitance Versus Voltage Tests EI Cid Testing of Stators & Rotors Rotor Bar Percentage Continuity Test Peak Pulse Scan test for Partial discharge AC High Potential Tests DC Step Voltage High Potential Tests Winding Data Verification Magnetic Core Saturation Tests Separation of Eddy Current and Hysteresis Loss
IR and PI Tests RSO Tests Impulse Tests Resistance and Impedance Tests Third Party Quality / Performance Inspections Stator Core Grinding / Etching and Testing On-Line Partial Discharge Tests Off-Line Partial Discharge Tests