Parallel operation of DC Generators
power is usually supplied from several generators of small ratings connected in parallel instead of from one large generator. It is also known as Advantages of Parallel Operation of DC Generators. This is due to the following reasons:
1. Continuity of service: If a single large generator is used in the power plant, then in case of its breakdown, the whole plant will be shut down.
- However, if power is supplied from a number of small units operating in parallel, then in case of failure of one unit, the continuity of supply can be maintained by other healthy units.
2. Efficiency: The generators efficiency at light loads is very low.
- So if a single unit is used it will be running at low efficiency at light loads. But if there are number of smaller units then at light load some of the generators may be switched off and thus providing maximum efficiency.
3. Maintenance: Generators generally require routine maintenance and repair.
- Therefore, if generators are operated in parallel, the routine or emergency operations can be performed by isolating the affected generator while load is being supplied by other units.
- This leads to both safety and economy.
4. Increasing plant capacity: In future world of increasing population, the use of electricity is continuously increasing.
- When added capacity is required, the new unit can be simply paralleled with the old units.
5. Non-availability of single large unit: In many situations, a single unit of desired large capacity may not be available. In that case a number of smaller units can be operated in parallel to meet the load requirement. Generally a single large unit is more expensive.
Conditions for Parallel Connection
- Entire load of the system should be distributed in all the generators.
- Check polarity of generator, If generator is connected with wrong polarity of the bar, it may result to a short circuit.
- Specification of each generator is different from one another. because of when they are synchronized together, their speed are locked into the overall speed of the system.