Woodward EPG electric speed regulator

Woodward EPG electric speed regulator

Overview

This manual covers models 512/524 and 1712/1724 of Woodward EPG (Electrically Powered Governor) electric governors, including synchronous models, covering installation, operation, calibration, troubleshooting, and other content. It is suitable for speed control of diesel, gas, and gasoline engines as well as gas turbines.

General information

Application scenario: Used to control the speed of diesel, gas, gasoline engines and gas turbines, suitable for prime movers of mechanical loads and generator loads. Parallel generator sets require additional equipment and Woodward generator load sensors.

Model selection: 512/1712 models are used for 12V systems, and 524/1724 models are used for 24V systems. The speed controller has four frequency ranges for magnetic and electric sensors, suitable for different engine types. The actuator has a dual end output shaft that can rotate clockwise or counterclockwise to increase fuel consumption. You can also choose to activate functions such as fuel limit and dual dynamic characteristics, and select compatible speed controllers and actuators according to the model selection table.

Attachment: Includes generator load sensor (for parallel generator applications), ramp generator (for slowing down acceleration and deceleration), external capacitor (providing exponential ramp), etc.

Reference materials: Relevant publications can be obtained from authorized Woodward distributors or AISF, and can also be viewed on the Woodward website.

Installation, inspection, and calibration

Installation of speed controller: The working temperature range is -40 to+75 ° C (-40 to+167 ° F), and it should be installed in a location with adjustment and wiring space, avoiding exposure to radiant heat sources, close to actuators and batteries to meet wire length requirements, and ensuring good ventilation.

Installation of actuator and linkage device: The operating temperature range of the actuator is -40 to+93 ° C (-40 to+200 ° F), avoiding exposure to excessive heat sources. Suitable linkage devices need to be selected to match the rotation direction of the actuator and fuel control, ensuring that the linkage device moves flexibly, without friction or clearance. The actuator includes a reset spring, which does not require additional addition.

Installation of magneto electric sensor: Installed through the shell or rigid bracket, ensure that the detected gear is made of magnetic material, and the gap between the sensor and the outer diameter of the gear is about 1.0 millimeter (0.04 inch) at the closest point. The gap can be set in a specific way and the anti loosening nut can be tightened.

Wiring instructions: Use a specific wiring diagram for wiring, and use insulated terminals for all connections. The wiring to the actuator and battery should be as short as possible, and different models have different maximum wiring lengths. Fuses and switches or circuit breakers should be located in non grounded battery leads, and the connection between the battery and the speed controller terminal should come directly from the terminal, without passing through the distribution point. Attention should also be paid to the shielding layer connection and the installation of varistors required by EMC.

Installation inspection: including checking electrical connections, installation of magneto electric sensors, fastening of actuators and linkage devices, testing battery voltage, terminal voltage, preset rated speed and idle speed, adjusting gain and stability, setting starting fuel limits, etc. There are additional inspection steps for different application scenarios (such as applications with 2500 ramp generators and parallel generators).

Operate

The governor needs to be powered on at startup and powered off at shutdown (if the fuel control is in the minimum fuel position, power off will cause shutdown). The application of parallel generators requires synchronous and parallel operation. In droop mode, parallel operation requires adjusting the speed and fine tuning potentiometer to set the power generation. The EPG design is suitable for unmanned operation, and the idle rated switch can be controlled by multiple devices. When using the Woodward SPM synchronizer for parallel generator applications, equivalent automation operation can be achieved. The ramp generator can be used to provide adjustable speed change time between rated and idle.

Describe

Speed control application: The basic speed control components include magneto electric sensors, speed controllers, and actuators, with two control loops: speed loop and current loop. The speed loop controller compares the expected speed with the actual speed, calculates the error signal, and adjusts the gain and stability to customize the governor response; The current loop ensures the correct driving of the actuator, including relevant circuits and protection mechanisms.

Executor: The mechanical structure is simple, with specially designed rotors and stators. The rotating design enables low-quality, low friction fuel control to achieve a certain angle of shaft rotation. When the magnetic circuit is energized, it provides torque in the direction of fuel increase, and the internal reset spring provides shaft torque in the direction of fuel decrease.

Application of using a ramp generator: slows down the speed change between idle and rated speed, without affecting steady-state speed, and controls the rate of change through acceleration and deceleration potentiometers.

Parallel generator application: Load sensors are used for synchronous or droop parallel connection. When isolating the bus, synchronous load distribution is usually selected. When parallel connected with infinite bus or incompatible electric speed controllers, droop operation is required.

Troubleshooting process

When there is a problem with the operation of the prime mover, it is necessary to first determine whether the fault is caused by the governor. The following methods can be used to troubleshoot:

Component replacement: Replace suspected faulty components with known normal ones.

System simplification: Gradually remove optional components and observe the performance changes after each removal.

Component testing: Test the output of suspected faulty components according to the manufacturer's instructions or known input and operating conditions.

When testing EPG, you can refer to the installation inspection steps in Chapter 2, where using a signal generator with isolated output for rated speed preset is the best way to test EPG speed control capability. If it involves the application of parallel generators, it is also necessary to refer to the inspection content of load sensors in the 82313 manual mentioned in Chapter 2.

Other inspection items

Unstable speed or power output

If the prime mover remains stable at certain speeds or power outputs but oscillates in other situations, it may be due to incompatibility between the linkage device and fuel control. Please refer to the "Linkage Device Compatibility" section under "Installation of actuators and linkage devices" in Chapter 2.

If there is a low-frequency oscillation of about 1Hz in the prime mover and the gain and stability adjustments in Chapter 2 are correct, it may be due to friction in the linkage device. It is necessary to disconnect the actuator from the fuel control, manually operate the fuel control linkage device, check whether it moves flexibly without friction or clearance, and lubricate or replace components if necessary.

Unstable load distribution

Verify if the current transformers (CTs) and voltage transformers (PTs) of the load sensor are wired correctly.

Check if the droop or cross current compensation settings of the voltage regulator are correct, and if there are intermittent faults or other issues with the voltage regulator.

If the problem persists, the load gain can be appropriately reduced and the load gain potentiometers of all other load sensors in the system can be set to have the same load signal at full load. In extreme cases, the load signal may need to be reduced to 3 volts. In this case, authorized dealers or Woodward can be consulted.

Fuse or circuit breaker issues

If the fuse or circuit breaker disconnects after the prime mover is running, it may be due to high voltage spikes generated by the battery or battery charger. It is necessary to separately wire from the speed controller to the battery terminal as shown at the top of Figure 2-6.

If the fuse or circuit breaker is disconnected during initial startup, it may be a battery connection error. It is necessary to verify whether the battery connection is correct, remove the wires from terminals 1 to 4, and check whether each wire is short circuited to ground.

Differences in performance between hot and cold states

If the prime mover oscillates in the cold state and stabilizes in the hot state, the gain potentiometer can be slightly rotated counterclockwise. If stability needs to be maintained, the stability potentiometer can be slightly rotated clockwise.