TYPES OF VOLTAGE REGULATORS FOR D.C. GENERATORS
Regulators for D.C. generators(Delco-Remy regulator) are made by different companies, the most famous of them are as follows:
- Delco-Remy regulator
- Auto-lite regulator
- Ford regulator
The working principle of these regulators is the same. Fig. 23. 10 shows a Delco-Remy regulator, designed by Delco-Remy Division of General Motors Corporation. It consists of a cutout relay, a voltage regulator and a current regulator. It is connected to the shunt-wound generator and battery of the car electrical system.
The voltage regulator maintains practically constant voltage in the electrical circuit. When the battery is low, it is supplied current at a high charging rate by the generator and when the battery is charged, the charge rate becomes slow.
The voltage regulator consists of two windings on a single core-a shunt winding of many turns of fine wire and series winding of a few turns of heavy wire. The shunt or voltage winding is connected at one end to the input side of the cutout and grounded to the other end.
The series or current winding is connected at one end to the field circuit of the generator and at the other end to the contact point of the armature. The armature above the windings is hinged and held in an upper position by a spiral spring. In this position, it closes a set of contact points which complete the generator field circuit through the series winding to ground.
When the battery is in a low stage of charge, the regulator does not operate. When the generator voltage reaches a predetermined value (7.2-8 volts or 13.6 15,8 volts) both the windings build up sufficient magnetic strength that pulls down the armature against spring tension. Thus, the contact points of the voltage regulator open, collapsing the magnetic field of the series winding. It also causes the field circuit to ground through the resistance.
This increased resistance in the generator field circuit reduces the current through it and hence the magnetic strength. This cuts down the generator output which reduces the current in the shunt coil. Because the magnetic field strength is reduced, the armature is again pulled back making the contact points closed. This directly grounds the generator field circuit again and the output increases.
The entire sequence is repeated many times a second, causing the resistance to be inserted into and removed from the generator field circuit as many as 200 times a second. This holds the voltage to a constant value. The constant voltage thus maintained becomes less and less able to send current into the battery because the battery voltage increases as it approaches a charged condition. Thus,
the charging rate is reduced in proportion to the condition of charge of the battery.
The current regulator is constructed in the sir similar manner as the voltage regulator,
except that the winding consists of a few turns of heavy wire connected in series with the generator armature so that the full generator current passes to the battery through the cutout relay. When the generator current reaches a set value, it creates sufficient magnetic force in the core which attracts the armature to open the contact point. This action adds resistance to the generator field to cut down the generator output. When the generator current is reduced, the magnetic force is also reduced, the spring tension pulls the armature to close the contact points. The generator field circuit is directly grounded. This causes the generator current to again increase. The cycle is repeated very rapidly, about 250 times a second, causing the current regulator to limit the current output of the generator to the rated value.
Explaining the working of Delco-Remy Regulator:
Both the regulators do not operate simultaneously, only one regulator can operate at a time. When the battery is low and load requirements are high, the current regulator operates to prevent the generator output from exceeding its safe maximum. When the battery is high and the load requirements are high, the voltage regulator operates to reduce the generator output. It falls below the value required to cause the current regulator to operate.
The voltage regulators and also some current regulators are temperature compensated. They have higher settings when cold than when hot. Temperature compensation of the voltage regulator allows the increase of voltage with low temperature. The current regulator is compensated to permit a higher generator output when the current regulator is cold than when it is hot. The generator output decreases as the temperature of the current regulator increases.
Applications Or Uses
The Delco-Remy Regulator used in the following vehicles:
Also, Read These Posts
- What is the DC Generator? Construction and Working Principle of DC Generator.
- What is AC Generator Or Alternator?
- What is Cutout Relay?
- What is Hydrometer?