Transformers can be connected in parallel, if they have the same primary and secondary voltages and equal operating frequency.
It enables an existing transformer to be upgraded to meet an increase in load, without having to remove that transformer and replace it with a 'larger' (expressed in volt amperes) one. It provides an useful way of using up a stock of smaller transformers.
Commutation Capacitors are usually switched in parallel to the thyristors.
the operation of connecting an alternator with other alternator or with common bus-bars is known as synchronizing.Generally alternator used in power system where they are connected in parallel with other alternator.condition for parallel operation of an alternator1. The terminal voltage of incoming alternator must be same as the bus-bars voltage.2. The speed of incoming alternator must be such that its frequency f =pn/120 as the same frequency of the bus-bars.3. The voltage of incoming alternator and the bus-bars voltage are in same phage.
Older ballasts with an iron core are basically an autotransformer. They transform voltage to a higher voltage with a single winding. Electronic transformers increase voltage with capacitors and diodes.
Power transformers can be used for power transformation. Voltage transformers are not suitable for high power applications.
You cannot connect transformers of different voltage in parallel. This is because circulating currents will be set up between the two transformers that may exceed their rated currents.
Division
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Paralleling transformers will increase the effective capacity available to the load. There are important requirements before transformers can be paralleled, so it's simply not the case of connecting any two transformers in parallel.
Followings are merits and demerits of parallel operations of transformers: Merits 1. Increasing load demand on substation can meet by connecting transformers in parallel. 2. Maintenance of individual transformer with low rating (Instead of one Big transformer with high rating)becomes easy and can be done without affecting power supply. 3. In case of any fault, faulty transformer can be removed from the system and others may continue feeding the load. 4. Power reliability of substation is increased. Demerits 1.Parallel operation needs very much attention and correctness. 2.Phase sequence , Voltage Ratings , % impedance drop and polarities these few things comes in picture which needs to be taken care when doing parallel operation.
There are basically two types of circuits: parallel and series. In a series circuit, current flows in one continuous straight path. In a parallel circuit, the current has more than one path to follow.AnswerThere are four categories of circuit, not two. These are 'series', 'parallel', 'series-parallel', and 'complex'. A 'complex circuit' describes any circuit not falling into the first three categories.
It is required to connect a second transformer in parallel with the first transformer if the load exceeds the rating of the transformer shown in Figure 1.46. The primary windings are connected to the supply bus bars while the secondary windings are connected to the load bus bars. During paralleling of the transformer, similar polarities of the transformers should be connected to the same bus bars shown in Figure 1.46. Otherwise, the two emfs induced in the secondary windings with incorrect polarities will produce the equivalent of a dead short circuit shown in Figure 1.47.The following conditions are important for parallel opera-tion of transformers:The voltage ratings of both the primary and the secondary of the transformers should be identical. Small differences are permissible if the resultant circulating currents can be tolerated.The connections of the transformers should be proper with respect to their polarities.The percentage impedances should be equal in magnitude and the X/R ratio must be the same to avoid circulating current and operation at different power factors.The equivalent impedances must be inversely proportional to the respective kVA ratings.The above conditions must be satisfied by paralleling transformers of identical ratings of the same make/model. With different kVA ratings of even the same make/model, the effects in steps 1, 2 and 3 may appear in undesirable amounts. Step 2 must be carried out satisfactorily even if steps 1, 3 and 4 are slightly modified.Figure 1.46 Parallel Operation of TransformersFigure 1.47 Parallel Operation of Transformers with Incorrect Polaritiesby keshav basyalpokharauniversitypokhara nepal
load demand
Knowing the polarity of transformers is important if they are to be connected in parallel.
The PT's (VT's) primary is connected between any two line conductors (or line to neutral). It's secondary is connected directly to the burden (e.g. voltmeter). If used together with a CT for the purpose of measuring power or energy, then its polarity markings must be observed.
It enables an existing transformer to be upgraded to meet an increase in load, without having to remove that transformer and replace it with a 'larger' (expressed in volt amperes) one. It provides an useful way of using up a stock of smaller transformers.
A: Transformers are designed for the maximum voltage they can sustain in operation a lower voltage operation should not bother them