7 factors to consider when deciding

1. 7 factors to consider when deciding Paralleling is the synchronous operation of two or more generator sets connected together on a common bus in order to supply common loads. In deciding whether one or more generators should be installed, various factors must be taken into account, such as: 1. Reliability 2. Performance 3. Cost 4. Generator and part size 5. Efficiency 6. Load variation 7. Flexibility 1. Reliability Reliability is the primary factor in deciding to use paralleling in most cases. emergency / standby applications , such as hospitals, computer centers and pumping stations; where power reliability is important since the connected loads are critical. In these cases, the use of multiple generator sets and the priority load of the system allow the most critical loads to be served at the expense of less critical loads. In systems where all loads are required for proper operation– Redundant generator sets are provided, so a failure of a generator set will not disable the installation. Paralleling normally requires the ability to sequence loads in stages and the ability to reduce loads to allow the generator sets to operate within their rated loads in the event of generator failure. A multiple assembly installation should be sized to allow a generator set to be removed from the system for routine maintenance or repair without compromising power to the load. 2.performance The performance of the on-site power system can be more like utility when the generator sets are in parallel, as the capacity of the aggregate generator sets against individual loads is much greater than it would be with a single. generator set serving separate loads. As the capacity of the bus is greater, the impact of transient loads applied to generator sets by individual loads is minimized. 3. Cost In general, multiple generator sets in parallel will cost more than a single generator set of the same capacity, unless the required capacity forces the design to work with machines. less than 1500 turns.

2. Parallel Generators The cost of a system should be evaluated as the total cost of ownership and should take into account factors such as: Available construction space Additional flue pipes and piping, Cable layout, Apparatus requirements and One system control for multiple installations. The required reliability and the resulting benefits must be weighed against the rising costs. Maintenance cost is a key factor with generator sets that operate on prime power or cogeneration schemes. While a single large assembly can have a seemingly high capital cost, this factor can be mitigated by other factors associated with the costs of installing a multi-generator system.

3. NOTE. When evaluating the total cost of ownership, the criticality of the installation will affect the decision about the degree of redundancy built into the system. Some local codes and standards require continuous service at legally required loads and the critical nature of some installations may require similar service provision. If the generator sets are paralleled, the maintenance costs and temporary downtime associated with temporary generator sets can be avoided. These considerations can also affect the number of sets required for installation. 4. Generator and part size The size of the generator and the room can be a critical factor and may force a decision towards single or multiple assembly installations . A single generator set will generally be much heavier than a corresponding machine used in a paralleling situation. For rooftop installations or when the assembly must be handled in a basement or other confined space, this can be prohibitive and lead to a decision in favor of smaller, lighter generators. However, the space required for access and maintenance must be allowed between machines in a multiple installation and these inevitably use more room volume per kilowatt of electricity generated . 5.effectiveness Efficiency is an essential factor if the power generation system produces base power or if it is used for tariff reduction or co-generation . The versatility of the paralleling system, allowing generator sets to operate at optimum load and maximum efficiency, often pays for initially higher installation costs in a short time in main power situations. 6.load variation Load is essential in deciding what type of installation is required. A single generator will generally be the most economical choice for loads less than around 2000 kW as the cost of the control and switching equipment in parallel will be large relative to the cost of the generator. For small but essential installations, where protection of two generator sets is essential, but the cost of paralleling equipment is prohibitive. A mutual aid installation can be a good alternative, in which one generator set acts in standby mode for the other. For larger loads , the choice is less simple and around 2 to 3 MW, solutions using one or more generators are available. Above 3 MW , the choice is almost always several generator installations. Note. Although at first glance more economical, a single generator solution is also the least versatile and may be less cost effective, especially for part loads and installations with long hours of operation. In high power applications, high speed diesel generator sets can provide lower overall life cycle cost , through higher efficiency and lower maintenance costs than larger, slower machines.

4. Load variation should be considered in any generator application decision as many applications have large differences between day and night load profiles and between summer and winter load profiles. A large manufacturing plant can have a daytime load of 2–3 MW ; but at night, unless used for continuous application, the load may drop a few hundred kW or even less . Installing a single large generator set in this application can result in many hours of light load, damaging to the engine. A typical installation of this type could use four 1000 kW generators , with a 500 kW generator in a paralleling scheme, where the daytime load uses three of the four series and at night only the smallest is needed. Transient loads have a large effect on the required size of a generator and it is important to consider all combinations of transient and steady state loads in any calculation to ensure that power quality is maintained. . Note that some loads have a large power factor load for the generator sets, and this must also be taken into account in the sizing and sequence of operation of the generator sets in the system. 7. Flexibility Flexibility can be an important factor to consider when an installation may change in the future. A single generator set installation is usually difficult to change, while sets can be added to a multiple set installation with relative ease, provided the initial design has taken this into account. This training video shows how a paralleling solution is configured with the Atlas Copco Qc4002 controller and five QAS generators. Risks. There are risks associated with the parallel operation of generators ; both between sets and with the provision of public services and these risks must be balanced with the benefits. The risks are: # 1 When proper load shedding has not been done provided the load is kept at a high level, there is a risk that in the event of a generator failure, the remaining generators in the system will not be able to support the load in the system. Load shedding should always be incorporated into a parallel generation scheme and the reserve capacity at any time during operation should correspond to the load that can be accepted in the event of failure of a running generator set. # 2 Not all generators can be paralleled– if assemblies from a different manufacturer or significantly different size need to be paralleled, consult your local Cummins distributor before proceeding. # 3

5. When paralleling with the utility, the generator effectively becomes part of the utility system. If the parallel operation with the distribution network is specified, additional protection is required for the protection of the generator and grid interconnection. This protection is usually specified and approved by the utility provider. Always consult local codes and standards when considering parallel operation of utilities. Burraq Engineering Solutions is the best training institute in Lahore which is providing practical training of Electrical Automation and Short Electrical Courses including PLC course, SOLAR SYSTEM Installation and DESIGN COURSE, ETAP course, DIALUX course, Panel FABRICATION course, VFD course, ADVANCED Control Panel, SWITCHERGEAR design course, Building Electrical design course, and all electrical diploma courses. Both online and physical classes available. We introduce a platform Lyskills from where you can get lifetime access to your desire courses at a very reasonable price.