The alternators on most modern vehicles have internal voltage regulators; therefore, they don’t need an exciter wire to function properly.
What is an exciter for an alternator?
Exciter or DC generator relay is a device which forces the DC machine-held excitation to build up during starting or which functions when the machine voltage has built up to a given value.
What are the 2 small wires on an alternator?
An alternator typically has two wires – a main connection (usually labelled B+) which delivers power to the car (and charges the battery) and an IND wire which feeds the internal exciter coils of the alternator. Without a current to the exciter coils, the alternator produces no output.
What are the 3 wires on an alternator?
The three wire types in a three-wire alternator include the battery positive wire, the voltage sensing wire, and the ignition input wire. The battery positive wire connects to the starter. The voltage sensing wire connects to the battery, and the ignition wire connects from the alternator to the key switch.
Why is excitation needed?
The excitation system is responsible for supplying the field current to the main rotor. The requirements of an excitation system include reliability under all conditions of service, a simplicity of control, ease of maintenance, stability and fast transient response.
What is the purpose of excitation system?
The basic function of an excitation system is to provide a continuous (DC) current to the field winding of a synchronous machine. This is achieved through the use of closed-loop control (or feedback control).
Can you wire alternator directly battery?
Attach a cable directly from the alternator output post to the positive side of the battery. This allows for full output from the alternator to the battery when heavy electrical demands are placed on the alternator. Wire the alternator controls.
Should alternator have power with key off?
“the power feed to the alternator is hot at all times whether the key is on or off… Is this normal with a 2 wire GM alternator? ” Yes, the Bat term on the alternator is connected directly to the battery, so battery voltage should always be present there.
What are the terminals on an alternator?
A key to identifying your alternator terminals
| Terminal | Definition | Notes |
|---|---|---|
| N | Neutral | Centre point of a Y-connected stator |
| P | Pulse | Stator connection for tachometer |
| R | Relay | Output to charge relays, etc |
| S | Sense | Battery Voltage sense wire |
What color wires go to the alternator?
Find the three cables that connect to the alternator terminals. You will see them hanging nearby: One is a red cable, the second black, while the third is usually a striped cable and may be colored green/yellow or blue/brown. The color can vary, but you can identify the cable, as it is thinner than the other two.
Why does alternator have 3 wires?
All alternators have a positive “output” wire, and a ground, either the case, or a separate wire. The third wire can be for a battery light, or a field “excitation” that may also involve the battery light. Some alternators have a separate “sense” wire, some just have the “output” and ground.
How does the alternator get excited initially?
Direct-connected direct-current (DC) generator
This method of excitation consists of a smaller direct-current (DC) generator fixed on the same shaft with the alternator. The DC generator generates a small amount of electricity just enough to excite the field coils of the connected alternator to generate electricity.
What happens when an alternator is said to be over excited?
An overexcited alternator always supplies lagging current to the connected load, which means that load is of lagging nature. Lagging load take active and reactive power from the supply or alternator.
What is excitation voltage in alternator?
An excitation voltage or current is the amount of electric energy ( D.C ) feed into the field winding of an alternator rotor to produce magnetic flux / field. The output voltage of an alternator depends upon the magnetic field and so the excitation voltage.
How does AVR work in alternator?
Automatic voltage regulators (AVRs) work by stabilizing the output voltage of generators at variable loads, but can also divide the reactive load between generators that are running in parallel (voltage droop), and helps the generator respond to overloads.
What is its role in AVR loop of the alternator?
It is necessary to provide constancy of the alternator terminal voltage during normal small and slow changes in the load. For this purpose the alternators are provided with Automatic Voltage Regulator (AVR). The exciter is the main component in the AVR loop. It delivers DC power to the alternator field.
Why we give DC excitation to the field of an alternator?
The primary reason lies in the principle of operation of Synchronous machines. The rotor acts as an electromagnet with a constant flux and gets interlocked with the rotating flux of stator to provide a constant speed rotation. The rotor needs to have a constant flux and that’s why the dc excitation is provided.
What happens if alternator is not grounded?
Poor ground connections are a cause of low charging output. There are positive and negative battery cable connections, the BAT+ power connection, and the engine ground strap. Overcharging can be caused by voltage dropping on the negative side.
Should there be power to the alternator?
If it is still not putting out sufficient power, then the alternator’s voltage regulator could be bad or the alternator itself may need replaced. A car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery.
Does alternator have constant power?
An alternator converts mechanical energy to electrical energy.The typical automotive alternator behaves like a constant voltage source. This means the alternator output post tries to maintain a certain voltage independently of shaft speed or electrical load.
Does an alternator need to be grounded?
The alternator is grounded to the engine block by its mounting points so the engine block itself becomes an electrical ground distribution block. You just need to find a suitable bolt to secure your additional ground wire. You can add a wire from the chassis of the car to the engine block.
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