Wimshurst Generator (Electrophorus Machine)

• Purpose: demonstration instrument for school physics classrooms — generation of large electric charges and a high potential difference, and demonstration of a spark discharge
• Operating principle: electrostatic induction — two coaxial discs with glued conductive sectors rotate towards each other, collecting brushes lead the separated charges to the conductors, and the Leyden jars store them until the air gap between the spark balls breaks down
• Disc diameter: 235 mm
• Spark discharge length: 3 cm
• Drive: manual, by turning the handle
• Charge storage: 2 Leyden jars
• Spark gap: ball type, on insulated holders, with adjustable gap
• Construction: all parts of the mechanism are mounted on sturdy electrically insulating stands, fixed together with the Leyden jars on a common insulating base
• Stand and base material: electrically insulating
• Contents: instrument, discharging rod
• Mains power: not required, the discs are turned by hand

Product passport: ULABS-P007 (PDF)

Preparation for Work

• Place the instrument on a dry horizontal demonstration table; the base should rest on all supports without rocking.
• Inspect the discs: the glued sectors should be intact, without peeling or scratches; the discs should turn freely, without touching each other or the stands.
• Adjust the collecting brushes so that their ends just touch the disc sectors along their whole length — excessive pressure slows the rotation and wears the sectors.
• Set the gap between the spark balls to 1-2 cm. The instrument works best in a dry room; in high humidity wipe the discs and insulating parts with a dry cloth and let them warm up.

Operation

• Turn the handle smoothly, gradually increasing speed; after a few turns a spark with a characteristic crack appears between the spark balls.
• The spark length is set by moving the balls apart or together; the largest gap that still produces a discharge corresponds to the highest voltage the instrument develops.
• For electrostatics experiments (sultans, electroscopes, charge distribution on a conductor) move the spark balls further apart than the spark length and feed charge to the object under test from the conductors.
• If no spark appears, stop turning, reverse the direction for a few turns, or prime the machine by briefly bringing a rod electrified by friction close to a conductor.
• When work is finished, stop the rotation and discharge the Leyden jars with the discharging rod.

Safety

• The instrument generates a high voltage; ignoring the safety rules can cause a painful electric shock, ignite flammable substances and damage nearby electronic devices.
• Do not touch the conductors, spark balls or Leyden jars while the discs are turning or immediately after they stop — the stored charge remains after the rotation ends.
• After every experiment discharge the Leyden jars with the supplied discharging rod, bringing the spark balls together until the sparking stops.
• People with implanted pacemakers and other electronic medical devices must not work with the product.
• Clear mobile phones, laptops, sensors and other electronic devices from the demonstration table: a spark discharge destroys them.
• Do not work near alcohol, ether or other flammable substances — a spark ignites them.
• The demonstration is performed by the teacher only; students stay 1 m away from the instrument.
• Check the fastenings, threaded joints and moving parts before every use, and set the instrument on a stable horizontal surface with free space around the moving parts.
• Recommended for learners aged 10 and older (grade 5 and up), under the supervision of a teacher.

Operating and Storage Conditions

• Air temperature: +5 °C to +40 °C
• Relative humidity: 40 % to 60 %
• Atmospheric pressure: 84 to 107 kPa (630-800 mm Hg)
• Store in a dry room at +5 °C to +40 °C and relative humidity of 60 %, covered against dust, with the spark balls moved apart and the Leyden jars discharged; keep the air free of impurities that corrode metals.

Maintenance

• Regularly wipe the discs, conductors and insulating stands with a dry soft lint-free cloth. Dust and damp film on the insulation create leakage currents and the instrument stops producing a spark.
• Do not lubricate the discs and insulating parts; a drop of machine oil is applied only to the rotation axles and drive bearings.
• Check the tension of the drive belts — belts that slip or have stretched are replaced. Watch the condition of the collecting brushes and straighten their fibres when needed.

Warranty and Disposal

• Warranty: 3 years, covering defect elimination and replacement of defective parts or equipment; spare parts and consumables available for 5 years.
• Disposal: the product is not electrical or electronic equipment and carries no WEEE marking; it contains no hazardous substances and is disposed of as municipal waste after separation by material.