Diesel generator maintenance training of the diesel engine -p91-p95 silicon rectification AC power generation ...

Diesel generator maintenance training diesel article -p91-p95 Silicon rectifier AC generator charging current instability

2 diesel generator silicon rectifier alternator charging current instability

The reason for the instability of the charging current of the silicon-rectifier alternator is that the charging circuit is in poor contact, and the contact between the generator brush and the slip ring or the contact of the silicon diode is disconnected.

When dealing with such failures, diesel generator maintenance personnel should first check whether the terminals above the generator are firm. If there is looseness or poor contact, they should be fastened. When the terminals are fastened and the charging current is still unstable, the ''F, the wiring on the connection terminals should be removed, and then the DC voltage of the multimeter should be used to measure the no-load between the “10” terminal and the generator case. Voltage. If you find that the multimeter's pointer oscillates back and forth, it is generally considered that the contact between the generator carbon brush and the slip ring is poor. At this time, check the pressure of the upper pressure spring of the carbon brush, the contact area of ​​the carbon brush and the slip ring, or whether the slip ring is too dirty. . When no faults are found in this part, the generator should be dismantled and the contact points of the silicon diodes, the windings, and the windings should be checked until the fault is cleared. *3. The charging current of the silicon rectifier alternator is too large.

The cause of this failure is the battery is seriously depleted or internal short circuit; generator wiring Du "F" and "ten" between the short-circuit phenomenon. In the event of such failure, maintenance personnel should quickly disconnect the diesel grounding switch (see Figure 2.127).

Then check for a short circuit between the "F" terminal and the "10" terminal. In the absence of a short circuit, other batteries should be replaced for inspection.

4. Inspection and maintenance tips for silicon-rectifier alternators When a silicon-rectifier alternator fails, it should first be checked from the external terminal of the generator. In the event that there is no fault such as grounding or loosening in the external terminal, the generator can be disassembled. . The main internal components of the generator are the excitation windings, the windings and the silicon diodes.

At present, the resistance value of the excitation winding of the silicon rectification alternator configured in the diesel engine is between 12-20 ohms.

The fault of the excitation winding can be judged by the visual method, and the multimeter can also be used to block the detection. If the measured resistance is basically within the above range, it should be considered normal; if the measured resistance is too small, it is generally considered that there is a short-circuit fault inside the excitation winding: if the resistance is found to be too large in the measurement, it can be considered as Excitation winding inside the phenomenon of disconnection or joint and slip ring welding and so on. When the internal winding of an excitation coil is open circuited, short-circuited or grid-ironed, the entire rotor should generally be replaced, and conditions can also be re-wound.

After the stator winding is burned out, it is generally checked with an intuitive method and then measured with a multimeter. If a short circuit or short-circuit fault occurs inside the stator winding, the winding should be made according to the diameter of the original high-strength enamelled copper wire, the factor of each phase series wire, the number of turns per coil, and the pitch of each coil. There are two kinds of lead of the silicon diode on the shell, the lead marked with red is the positive lead, and the lead marked with black is the negative lead. Under normal conditions, the positive nozzle value should be small and the reverse resistance value should be large (10k ohms or more).

If the measured positive resistance is large, it is generally considered that the silicon diode has a poor contact or disconnection phenomenon: If the measured positive and negative resistance values ​​are small, it can be generally judged that a short circuit occurs inside the silicon diode. Regardless of whether a short circuit fault or open circuit fault occurs inside the silicon diode, a new silicon diode should be replaced. During assembly, the silicon diode should be pressed into the hole, and it must not be struck with a hammer to prevent internal damage of the silicon diode.

V. Regulators

The voltage of the diesel generator set silicon-rectifier alternator varies with the speed of the diesel engine. Because the voltage is unstable and affects normal use, a voltage regulator is required in the circuit.

The oil machine keeps the voltage constant at different speeds.

The physical appearance of the regulator is shown in Figure 2-128. It consists of a core, a magnetized coil, a spring, a magnetic yoke, an armature, contacts, contact holders, and additional resistors, as shown in Figure 2-129.

The working principle of the diesel generator regulator is: through the contact closure and disconnection, or in the excitation circuit in series with an additional resistor to change the size of the excitation current, so as to achieve the purpose of controlling the output voltage. The closing and breaking of the contacts is determined by the magnitude of the magnetic force generated by the core.

In order to avoid the role of power equipment regulator is the regulator in the course of the use of prone to contact erosion or contact surface inequality failure, sometimes there will be resistance to break or short circuit coil, open circuit and other failures. When the contacts are ablated or uneven, use “o” fine sand paper or platinum sand bars to polish the contacts and ensure that the contact surface is above 85%. When the amount of damage to the coil cannot be repaired, the new regulator must be rewinded or replaced as required. Replace the resistor when the resistance is disconnected