IS215VPROH1B - VME PROTECTION ASSEMBLY

Functional Description

The IS215VPROH1B is a Turbine Protection Board designed for the Mark VI system. The Turbine Protection Board (VPRO) and its associated terminal boards (TPRO and TREG) provide an independent emergency overspeed protection system. The protection system consists of three redundant VPRO boards in a module separate from the turbine control system, which control the trip solenoids via TREG. VPRO also has an Ethernet connection for IONet communications with the control modules.

Functional Description

• The VPRO board in Protection Module P performs the emergency trip function. Up to three trip solenoids can be connected between the TREG and TRPG terminal boards.
• TREG supplies the positive side of the 125 V dc to the solenoids, while TRPG supplies the negative side. Either board has the ability to trip the turbine.
• VPRO offers emergency Overspeed protection as well as emergency stop functions. It is in charge of TREG's 12 relays, nine of which form three groups of three to control the three trip solenoids. VPROH1A has been replaced by the functionally equivalent VPROH1B. VPROH1A and VPROH1B support a second TREG board that is powered by VPRO connector J4.

Speed Control and Overspeed Protection

Six passive, magnetic speed pickups are used to implement speed control and overspeed protection. The controllers monitor the first three, which use the median signal for speed control and primary overspeed protection. The second three are connected to the R8, S8, and T8 VPROs in the protection module separately. On the TPRO terminal board, nine passive magnetic speed pickups or active pulse rate transducers (TTL type) are provided, with three monitored by each of the R8, S8, and T8 VPROs. The application software has separate overspeed trip settings for the primary and emergency overspeed trip limits, and a second emergency overspeed trip limit must be programmed into the I/O configurator to confirm the EOS trip point.

Interface to Trip Solenoids

The trip system combines the controller's Primary Trip Interface with the protection module's EOS Trip Interface. To interface with the hydraulics, three separate, triple redundant trip solenoids (also known as Electrical Trip Devices - ETDs) are used. The TRPG and TREG terminal boards are linked by the ETDs. From the turbine control, a separately fused 125 V dc feeder is provided for each solenoid, which energizes in the run mode and de-energizes in the trip mode.

Backup Synch Check Protection

The Protection Module includes backup synch check protection. The generator and bus voltages are supplied by two single-phase potential transformers (PTs) with secondary outputs of 115 V rms. Between the PTs and the turbine control, the maximum cable length is 100 meters of 18 AWG twisted, shielded wire. Each PT is magnetically isolated, with a rated barrier of 1,500 V rms and a circuit load of less than 3 VA. Synchronization algorithms are based on phase lock loop techniques. At nominal voltage and 50/60 Hz, the phase error between the generator and bus voltages is less than +/-1 degree. The measured frequency is within 0.05% of the input frequency and supports a frequency range of 45 to 66 Hz.

Diagnostics

Three LEDs at the top of the VPRO front panel indicate status. The normal RUN condition is a flashing green, while the FAIL condition is a solid red. The third LED is STATUS, which is normally off but displays a steady orange if the board has a diagnostic alarm condition. VPRO performs diagnostic checks and generates faults in the following ways:

• Feedback from the trip relay driver and contacts
• Solenoid voltage and source of solenoid voltage
• Economizer relay driver and contact feedbacks
• Relay driver and coil K25A
• Contact feedback and servo clamp relay driver
• All analog inputs have high and low limits.

If any of the above signals fails, a composite diagnostic alarm L3DIAG VPROR, S, or T is generated. Individual diagnostic signals can be latched and then reset with the RESET DIA signal if they become healthy.

Features

• The Board protects against backup synch checks and detects speed differences.
• The thermocouple and analog inputs are both supported by the board. Two circuit boards are stacked one on top of the other in this module.
• The top board, an IS200VPRW, is inserted into standoffs and connects to the lower board by four screw connections. Integrated circuits, a transformer, multiple transistors, as well as resistors, capacitors, and diodes, are all present on the board. Carbon composite material is sometimes used to make resistors.
• There are various inductor coils on the board, as well as numerous connectors, including plugs. A heat sink can be found on the right front side.
• The module's bottom board has two backplanes. There are capacitors and resistors, as well as many integrated circuits, in it. Oscillating chips are included in this category. The top board's standoffs are set towards the board's margins.
• The module uses the TREG board to regulate trip solenoids. The controller's application software is used to start tests on these trip solenoids. These can also be tripped manually.
• A faceplate is included with the board. LED indicators, a power switch, cable connectors, and Ethernet connectors are all found on the faceplate. Screws attach this faceplate to the boards.

Installation

To install the VPRO board, follow the steps below:

1. Turn off the VME I/O processor rack.
2. Insert the VPRO board and use your hands to push the top and bottom levers in to seat the edge connectors.
3. Tighten the captive screws on the front panel's top and bottom.
4. Power up the VME rack and check the diagnostic lights at the top of the front panel.

Cable Connections

Cable connections to the TPRO and TREG terminal boards are made at the VPRO front panel connectors J3, J4, J5, and J6. These are latching connectors to secure the cables. J7 is a 125 V dc power connector.

Refer to the section on diagnostics in this document for more information. You may need to update the VPRO firmware to the most recent version.

Operation

The protection module is designed to protect the turbine from emergency overspeed (EOS) and other critical conditions. Key features include:

Key Features

1. The main purpose of the protection module is to protect the turbine from emergency overspeed (EOS) using three VPRO boards. Additionally, it includes backup synchronization check protection, three analog current inputs, and nine thermocouple inputs, primarily for gas turbine exhaust over-temperature protection.
2. The protection module is triple redundant, with three completely separate and independent VPRO boards named R8, S8, and T8 (previously X, Y, and Z). These boards ensure that the protection system remains operational even if one board is powered down or replaced.
3. Each VPRO board has its own I/O interface, processor, power supply, and Ethernet communications with the controller (IONet). These communications allow the controller to send test commands to the protection module and monitor EOS system diagnostics both in the controller and on the operator interface.
4. The VPRO board is the heart of the protection system, facilitating communication between the protection module and the control system. It has a VME interface for programming and testing in a VME rack. However, when plugged into the protection module, the backplane is neutralized, ensuring there is no continuity between the three independent sections.