Problem Outline for Automatic Voltage Regulators
    Add a header to begin generating the table of contents

    What is AVR? What does AVR do?

    AVR is the abbreviation of voltage automatic regulator, which is used to adjust the voltage. AVR is generally used in excitation generator, mainly to adjust the generator output voltage and control the internal excitation voltage, its essence is a feedback circuit. When the generator load increases, the voltage above the generator coil will drop, this signal will be transmitted to the AVR, and then the AVR automatically increases the upper limit of the output voltage, the output voltage of the generator will come up. And the excitation current output from the carbon brush is also output to the carbon brush after the regulation of AVR. The excitation regulator, by measuring the generator voltage and comparing it with the given value, continuously adjusts the excitation current with the change of the electric load to make the generator voltage stable at the set value. The electronic voltage regulator, which excites the motor and obtains the voltage through the generator’s sampling winding, changes the output voltage by adjusting the excitation current to the rotor to be larger or smaller.

    The main function of the generator voltage regulator

    Main functions of the generator voltage regulator The voltage regulator has three main functions: maintaining the voltage at a given level, adjusting the differential function, and improving the stability of the power system:
    ① Maintain the voltage of the generator to a given level. As the change of load current has an impact on the end voltage of the generator, the end voltage changes too much will produce many unfavorable factors and problems for the power system and power equipment, so the excitation current of the generator must adapt to the change of voltage and give a rapid and automatic adjustment in time.

    ② Reasonable distribution of load between parallel generator sets. The grid is operated by multiple generators in parallel, and the load carried by each unit should be reasonably distributed, otherwise it will cause overload of some generators. The voltage regulator is therefore required to share the load of the grid smoothly according to a specified rule. This function is also called the voltage regulator’s adjustment function.

    ③Improve the stability of the power system.

    The relationship between generator excitation regulator and governor?

    The speed regulation of the generator is actually determined by the diesel engine (or other power source), while the excitation system of the generator is regulated according to the voltage at the output.

    Generally there are two cases to be divided.
    1, for grid-connected generator sets, the speed of the oil engine is more constant, the generator excitation regulator only according to the size of the output voltage to adjust, that is, the voltage is high to reduce the excitation current; low voltage to increase the excitation current.
    2, for a single generator (or a small system of the generator set), and the load is a variable speed load, the generator set control is more complex.
    In this case, the output of the generator is generally required to be a constant voltage to frequency ratio output; this requires a constant voltage to frequency ratio regulation in addition to the two aforementioned control cycles (speed regulation and excitation regulation). In other words, when the load requires low speed, the speed of the oil engine needs to be controlled to reduce to the required range; and vice versa.

    What should I pay attention to when connecting the generator set voltage regulator?

    Generator set voltage regulator connection line needs to pay attention to the following matters.

    1, the generator voltage regulator connection line can not be connected to the wrong, its out of the head 2 and 3 of the signal and power in and out of the generator tap line, its voltage is 200V, can not be connected to 400V up, otherwise it will cause burnout.

    2, shut down the generator set, the first an should check the reasons, such as: fuses, wiring, remanent voltage, etc..
    Do not blindly go to the voltage regulator adjustable potentiometer and magnetization 8, diesel engine idle, do not go to adjust the voltage regulator and magnetization.

    3, the two external potentiometer appearing head 1, 2, when not connected to the potentiometer can not be disconnected, when connected to the potentiometer, the potentiometer can not be open circuit, otherwise it is easy to cause damage.

    4, magnetic field sprint do not use 24 V battery, need to use 12 V battery, magnetizing the unit must be in a static state, otherwise it may cause high point smoke damage to the regulator.

    5, 50HZ, 60HZ2 use to pay attention to the correct wiring, otherwise affect the normal use of the regulator.

    How to deal with the voltage instability of diesel generator sets?

    Diesel generator set voltage instability causes and solutions.

    1, the wire wiring part of the loose Check the diesel generator set each connection part, and with repair.

    2, the control panel voltage – current selection switch failure Replace the diesel generator set switch.

    3, the control panel voltage adjustment resistor failure Replace the voltage regulator resistor.

    4, the voltage table failure, the display voltage is unstable replace the new voltage table.

    5, generator voltage regulator is bad or not adjusted regulator Check carefully whether the voltage regulator is bad or not adjusted in place. Instantly replace or adjust.

    6, may be caused by excessive vibration in the operation of the diesel generator set Instantly check whether the generator set shock pad damage or unbalance the unit.

    7, may be the engine speed instability caused by unstable voltage Adjust or change the diesel fuel system parts to make its speed stable

    Explanation of generator over-excitation, under-excitation, late-phase operation, and advanced-phase operation?

    When the excitation current is adjusted, it is E that changes, and the stator current and power factor of the generator also change.

    1, the stator current is kept at a minimum, at this time cosφ=1, this case is called normal excitation of the generator, the generator only emits active power.
    2, on the basis of normal excitation to increase the generator excitation current, at this time E2>E1, called over-excitation, stator current I behind the terminal voltage U, the generator in addition to the grid to send active power, but also to the grid inductive reactive power.
    3, on the basis of normal excitation to reduce the generator excitation current, then E3 < E1, known as under-excitation, stator current I ahead of the terminal voltage U, the generator in addition to active power to the grid, but also to the grid issued capacitive reactive power, can also be said to absorb inductive reactive power from the grid.
    4, the generator late phase operation, supply system active power and inductive reactive power, its active power meter and reactive power meter are positive; into phase operation, supply system active power and capacitive reactive power, its active power meter indicates a positive value, the reactive power meter indicates a negative value.

    Brushless generator AVR fault judgment skills?

    When the brushless generator does not generate electricity, it is impossible to determine whether it is caused by AVR fault, and do not know where to start checking, the following is a brushless generator AVR fault determination skills.

    1: Open the brushless generator AVR shield, pull off the AVR on F1 and F2 plug-in.

    2: Use 2 power cables of about 1 square, connect one end to the positive and negative terminals of the 12V starter battery, and the other end to the excitation coils F1 and F2 respectively. Note that the positive terminal of the battery is connected to F1 and the negative terminal is connected to F2.

    3: Turn on the starter power switch, start the diesel generator to 1500 rpm to observe the change in generator voltage and frequency.

    4: When using this method, pay attention to the safety of electricity, please do not misconnection and line shorting and accidents.

    5: If the diesel generator speed increases, the voltage rises, when the generator speed to 50HZ voltage is 400V. so judge brushless generator AVR damage caused by not generating electricity, change the generator AVR. conversely, when the diesel generator speed changes and the voltage and frequency does not change judge the generator does not generate electricity cause not AVR fault. Check and repair from other paths.

    What are the reasons for the unbalanced three-phase current of the stator during the operation of the generator? How to deal with it?

    A : The main reasons are:

    1. Internal faults of the generator, such as: stator winding inter-turn short circuit, winding disconnection;
    2. Three-phase unbalance of system load: if the system has asymmetric loads such as single-phase electric furnace and electric locomotive;
    3. System Asymmetric fault occurs and the protection refuses to act;
    4. The main circuit breaker of the generator is not running in all phases.

    Treatment methods:
    1. Ask whether the dispatch is caused by the system. If it is caused by the system, the difference between the three-phase current imbalance should be controlled within 8%Ie by adjusting the active and reactive loads of the generator, and the maximum phase should not exceed the rated value.
    2. Deal with the non-full-phase fault of the main circuit breaker of the generator.
    3. If it is not caused by the system failure and the main circuit breaker, a comprehensive inspection of the generator, transformer outlet, etc. should be carried out, and a power failure inspection can be carried out if necessary.
    4. During the three-phase current unbalanced operation, the rotor temperature of the generator should be closely monitored and the temperature should not exceed the allowable value.

    The role of ship generator AVR

    The marine generator AVR serves the following purposes.

    (1) To maintain the terminal voltage of the generator constant under the normal operating conditions of the ship’s power system.

    (2) To maintain the stability of the parallel operation of the generating sets and to reasonably distribute the reactive power among the parallel generators.

    (3)To improve the stability of parallel operation of generator sets and the reliability of other relay protection actions when a short-circuit fault occurs in the ship’s power system, to be able to forcibly excite the excitation system.

    What is the role of generator excitation voltage regulator (AVR)?

    A: The excitation voltage regulating plate is an indispensable device in the excitation system. It is mainly used to limit, control and protect all the necessary functions of a generator working within its capacity. Generally, there is a difference adjustment, and the excitation current is adjusted according to a certain difference adjustment parameter by sampling the machine terminal voltage in time to stabilize the machine terminal voltage. The principle is to control the output voltage, reactive power or power factor of the synchronous generator by changing or controlling the DC excitation level of the exciter magnetic field output to the generator. The whole generator set includes generator, steam turbine and excitation system.

    Some generator voltage regulators need to be charged and magnetized. What is the reason?

    A : First, check the output voltage when it is not magnetized. If it is greater than 5VAC, it is because the magnetizing voltage required by the AVR is relatively high. If it is less than 4.5VAC, it is because the remanence is too low and needs to be magnetized.

    Is the GAVR-8A generator voltage regulator plate current limiting type or loss type?

    A: All of our generator AVRs are current-limiting type, and most of them are thyristor phase modulation mode, and a few are PWM mode.
    Features of GAVR-8A generator voltage regulator board: 1. Voltage regulation accuracy < ±1% 2. Suitable for 220/380VAC brushless generators. 3. 5A DC large output current 4. Select 50/60 Hz by connecting copper sheets. 5. Small size, light weight and strong weather resistance. 6. With low frequency protection and slow voltage build-up function. 7. With EMI suppression circuit. 8, with high breaking capacity fuse protection.

    Problems with the contacts or contacts of the generator voltage regulator

    Generator voltage regulator contact or contact in the normal operation of the current allowed through should ensure that no damage due to heat, but more attention should be paid when the generator voltage regulator contact or contact cut off the circuit, to prevent the contact surface burned due to sparking. Sometimes the generator automatic voltage regulator in this case can even partially melt the contact curve, the size of the spark when cutting off the current in addition to the supply voltage, but also with the type of load related.

    Inductive loads produce inductive potential when the power is cut off, its value often exceeds the supply voltage. Therefore, in the relay manual for different types of loads often specify the corresponding current value.

    Note: The series or parallel connection of multiple contacts does not necessarily increase the cut-off capacity exponentially, because each contact on the same relay can not be connected and disconnected at the same time, in parallel and in series with the first disconnected contact, there is a risk of destruction.

    Increase the cut-off capacity of the method, in addition to the use of intermediate relays or change the selection of larger relays, can be used to eliminate the spark circuit for smaller sparks (commonly used in automatic voltage regulator relay). Or the use of interrupter Qin, interrupter grid and other devices to eliminate the larger arc (commonly used on the SE350 contactor).

    For AC circuits, because the arc is easily extinguished at the moment of crossing zero, the value of the current allowed to be cut off is larger than that of DC circuits.

    How to deal with the black smoke from Cummins generator voltage regulator plate?

    A: First of all, you need to check whether the air filter is blocked, exhaust back pressure, oil nozzle, lack of tightening force of the actuator cylinder, etc.

    1. Cause:

    1) The air filter is severely blocked

    2) Fuel trademark criticism

    3) Exhaust back pressure is too large

    4) Failure of the fuel injection pump

    5) Oil nozzle bites to death

    6) Lack of tightening force of Cummins actuator cylinder

    2. Disposal method:

    1) Check whether the air filter can fail

    2) Check the fuel quality

    3) Reflect. Lang is readjusted from the oil supply by the pump

    4) Introspect. Abandoned by the nozzle atomization

    5) Check whether the cylinder tightening force is normal

    How to adjust the generator to replace the automatic voltage regulator (AVR) before it can be connected to the grid?

    It is not possible to connect to the grid manually when replacing the generator automatic voltage regulator (AVR). The prerequisite for grid connection is the synchronization of frequency, voltage and phase sequence, which requires the configuration of a special diesel generator grid connection controller for real-time monitoring of the state of the grid and the diesel generator, and collection. At the same time, adjust the voltage and frequency of diesel generators to ensure consistency with the grid. In addition: from the safety consideration of the diesel generator output should be installed with intelligent circuit breakers, when there is an abnormal situation intelligent circuit breakers can trip protection.

    Before connecting to the grid requires phase sequence synchronization and then adjust.

    1, respectively, adjust the voltage and frequency so that the two units are consistent.

    2、Adjust the power distribution respectively.

    3, respectively, adjust the reverse power, you speak of the situation is out of step, the appearance of reverse power.

    4, adjust the parallel load switch. Parallel adjustment of the situation parallel loop current is zero. Meet these requirements can achieve grid paralleling.

    How to judge the quality of the voltage regulating plate (AVR)?

    To determine whether the regulator board (AVR) is good or bad, under the premise of confirming that the winding coils are normal, find out the F1.F2 excitation power line, use the battery as the power source for magnetization, connect the positive pole to F1 and the negative pole to F2 (to be connected), when the starter unit reaches the rated speed, connect F2 to the negative pole of the battery, the following conditions may occur:

    1: there is a voltage established ≥ 400V (according to the size of the battery voltage and decide), use a multimeter to check P2.P3.P4AVR detection voltage there is no AC190-220V, if there is that the detection line is normal, and then check the AVR on F1, F2 there is no DC40-90V voltage output, if there is to prove that the regulator (AVR) is intact If there is no DC voltage output or very low, prove that the AVR has been bad.

    2: If there is no voltage established or DC voltage ≤ 30V, to determine the normal windings, it is basically certain that the exciter rectifier secondary tube or surge elimination tube damage, should exclude AVR fault, should focus on checking the rectifier diode.

    Sharing is caring!

    Shopping Cart
    Scroll to Top