IS215VPROH1B(IS215VPROH1BD) GE VME PROTECTION ASSEMBLY

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 VPROH1A has been replaced by the functionally equivalent VPROH1B.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.

IS215VPROH1B Installation

To install the VPRO board

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 to the TPRO and TREG terminal boards are made at the VPRO front panel connectors J3, J4, J5, and J6. To secure the cables, these are latching connectors. 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.

IS215VPROH1B Operation

• The main purpose of the protection module is to protect the turbine from emergency overspeed (EOS) using three VPRO boards. VPRO also has backup synchronization check protection, three analog current inputs, and nine thermocouple inputs, which are primarily intended for gas turbine exhaust over-temperature protection.
• With three completely separate and independent VPRO boards named R8, S8, and T8, the protection module is always triple redundant (originally named X, Y, and Z). While the turbine is running, any of these boards can be powered down and replaced without jeopardizing the protection system.
• Each board has its own I/O interface, processor, power supply, and Ethernet communications to the controller (IONet). The communications allow the controller to send test commands to the protection module and monitor EOS system diagnostics in the controller and on the operator interface.
• The VPRO board, which serves as the system's heart, is where communications take place. The VPRO board has a VME interface for programming and testing in a VME rack; however, when plugged into the protection module, the backplane is neutralized, removing any continuity between the three independent sections.

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.