VOLTAGE SPIKES DUE TO LARGE INDUCTIVE LOADS
Normally referred to as a voltage spike, it is a sudden short duration, high amplitude disturbances in the normal voltage levels. Apart from lightening, most are caused by the switching on and off of internal and external loads, and occur regularly on any power system. Transients can be transmitted to all parts of the building via the electrical wiring. A frequent power disturbance seen in building wiring systems today is transient voltage associated with inductive loads. These disturbances are as a result of switching inductive electrical equipment on and off in the vicinity of a sensitive device such as an electronic transformer or ballast. It is an electrical device using conductive coil windings to produce an electro magnetic field that in turn drives the motor or equipment. Inductive loads exhibit inrush current when energized, which may be many times the operating current. These loads can produce significant voltage spikes due to inductive “inrush current”. The voltage spikes can be transformed back into the primary of the electronic device, where they have the potential to damage circuitry. Also when de-energized, the magnetic field collapses, again generating a high "back current". Common inductor type equipment includes: mechanical tools, air conditioners, refrigerators, air compressors, pumps, dishwashers, dryers, electric motors, fans, fluorescent lighting, high intensity discharge lighting (such as metal halide), and other equipment with heavy starting loads. Generally speaking, electronic devices are for resistive loads and must not be on the same circuit as inductive loads. However, these days most electronic devices are designed with a certain amount of protection against voltage spikes, and are fairly tolerant of inductive loads. However they may not be able to cope with very heavy loads such as a large bank of fluorescnet fittings, or heavy machinery. The voltage spikes may cause immediate failure, or more likely, minor damage that degrades the performance of the components over time. Firstly check if there are inductive load issues on site. If there are, check the specifications or check with the supplier if the product being considered is suitable. 1) Isolation: If the offending inductor type fitting is on the same circuit you can be sure this is the problem, and it will have to be removed off the circuit.
What is a voltage transient?
What is an inductive load?
What may happen?
How to avoid problems?
Solutions to existing problems?
2) Voltage regulation: General surge protection to the building will not be the answer where internal inductors are the problem. The answer would be to provide regulation to particular circuits. This solution may or may not be easy, depending on the existing electrcial installtion.
3) Mechanical transformers or ballasts: These are inductors themselves, so this option is a practical solution.
4) 240V fittings: Again, a practical and easy solution. An incandescent lamp is more resilient to transients than microprocessor components in electronic devices.
5) Replacement: Where inductive loads have not been considered, and the above suggestions are not acceptable, the last option is to replace the installation or fittings.