tpd

11

Presentation

By

C&I Division, Triveni Engineering & Industries Ltd., Khatauli.

“Turbine Protective Devices”

27-11-2008, @ 11AM & 4PM; Conference Hall

K.R.RAO, AGM (C&I)

22

C&I Division, Triveni Engineering & Industries Ltd., Khatauli.

24 MWDouble Extraction cum Condensate type

33

TRIVENI ENGINEERING & INDUSTRIES LTD, COGEN POWER PLANT,KHATAULITRIVENI ENGINEERING & INDUSTRIES LTD, COGEN POWER PLANT,KHATAULI..

C&I DIVISION KRRAOO&M Training Programme

Turbine Protective Devices

Tripping Device

Over Speed Trip

SOV for remote tripping

Casing Expansion

Differential Expansion

Axial Displacement

Bearing Vibrations

Bearing Temperatures

Low Lube Oil Pr.

Low Vacuum

Hi/Lo Extrn. Pr.

Extrn./Exhaust Temp

Generator Protection

Manual/Remote Trip

Casing/Rotor Temp.

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44



Turbine Protective DevicesTripping Device

When ever the turbine is to be tripped , the Governing oil pressure is drained by tripping device.

Thus pressure in front of stop valve piston disc and control oil pressure falls, resulting in closure of stop valve and control valves.

55



OVER SPEED TRIP

Pro Tech 203

Woodward

Over speed protection

MPU-1

MPU-2

MPU-3Turbine Trips

>6070 rpm


The over speed protection is formed by three independent sensors of turbine speed evaluation that act through a selection of the output signaltwo of three after exceeding a set value of security speed for an immediate impulse for closing of the ESV within less than 30ms.

Normal speed-5500rpm

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TRIVENI ENGINEERING & INDUSTRIES LTD, COGEN POWER PLANT, KHATAULTRIVENI ENGINEERING & INDUSTRIES LTD, COGEN POWER PLANT, KHATAULII..



Magnetic Pickup

A magnetic pickup consists of a permanent magnet, wrapped with a coilof a few thousands turns of fine enameled copper wire.

When discrete ferromagnetic object such as gear teeth or blades arepassed through the probes magnetic field, the flux density is modulated.This induces AC voltages in the coil. One complete cycle of voltage is generated for each object passed.

The total number of cycles will be a measure of the total rotation, andThe frequency of the AC voltage will be directly proportional to the rotational speed of the shaft.

MPU HZ = No. of Teeth X Gear rpm60

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TRIVENI ENGINEERING & INDUSTRIES LTD, COGEN POWER PLANT, KHATAULTRIVENI ENGINEERING & INDUSTRIES LTD, COGEN POWER PLANT, KHATAULII..



Magnetic Pickup

NS

Ferrous Gear

Gap

CoilMagnetic flux

1.5 VAC

88




Magnetic Pickup

NS

CON

DU

CTO

R

Making and breaking of the flux lines induces an alternating voltageinto the coil around the pole piece.

Each pulse is represented by a gear tooth passing by the MPU.The impedance of MPU is approximately 220 ohms.

99




PROXIMITOR

CON

DU

CTO

R

PR

OX

IMIT

OR

RF SignalOscillatorDemodulator

ExtensionCable Probe

1010




PROXIMITOR (Eddy Current Probe)

The mechanical energy is transformed into electrical energy using the proximityTransducer system. The interface device used for this system is called a proximitor.It generates a radial frequency(RF) signal using an oscillator circuit. The RF signal is transmitted from the probe coil which creates an RF field around the probe tip.When conductive material is present in the RF field, Eddy currents flow in the surface of that material. Once the probe is close enough to cause eddy currents to flow in a conductive material the RF signal is affected in two ways.

1. Amplitude is minimum, when the Gap is less.2. Amplitude is maximum, when the Gap is more.

If the target is moving slowly within RF field, the signal amplitude will increaseor decrease slowly. Depending on the movement of target, the amplitude increaseor decrease slowly or rapidly. This oscillatory movements of the target causes theRF signal to modulate.

1111




PROXIMITOR (Eddy Current Probe)

This will be convert by demodulator and will give a AC signal (sine wave).If the target is oscillating (gap changing slowly or rapidly), the proximitors outputalso vary the DC voltage (AC) shown above by a sine wave.If the probe is observing a vibration, the proximitor will provide both a DC (gap) and an AC (vibration) component in the output signal.The frequency response from 0 Hz to 10 kHz.

1212




Casing Expansion

This is the measurement of Turbine Casing or Shell moves in relation to a fixed location usually measured with a LVDT (Linear variabledifferential Transformer). Case expansion is the Thermal growth of the machine case as It expands during machine startup and on line operations.

Thermal growth at different rates can cause internal rubbing betweenrotating and stationary parts of the machine.

The case expansion transducer system uses the LVDT to measure themachine Case thermal growth.

A rod on the LVDT connects to the machine. As the machine case grows, the rod moves inside the LVDT. This causes a change in the signal in the LVDT.

Range:- 0 ~ 25mm; Trip:- 20mm

1313




Rotor ExpansionDuring turbine startup, extra care must be taken to ensure that the case hasbeen properly heated and expanded sufficiently to prevent contact between the rotor and the case.

For this Eddy probe transducer will generate a high frequency oscillating RF signalsthat is sent through the extension cable to the pickup tip. The pickup tip having awound coil of fine wire, radiates a electromagnetic Field, as the radiated field is bisected by the rotor surface. As the rotor surface moves closer to the pickup tip, a greater amount of eddy currents are created Proportional to the gap betweenthe surface and the pickup tip. The signal sensor contains a demodulator which measure the increase in eddy currents, and generates an equivalent DC voltage proportional to the gap.

Rotor Expansion on a turbine is the absolute measurement of the rotor's axial thermal growth with respect to the turbine's foundation.

1414




Differential Expansion

This is very important parameter receiving much attention during turbinestartup and warming. This parameter measures how the turbine rotorexpands in relation to the turbine shell or casing. The difference betweenCasing expansion & rotor expansion is called differential expansion.It is the relative measurement of the rotor’s axial thermal growth withrespect to the casing.

Casing expansion with respect to turbine’s foundation.Rotor expansion with respect to turbine’s foundation.Rotor expansion with respect to the casing is differential expansion

Range:- -4mm to 6mmAlarm :- +2.30mm & -1.60mmTrip:- +3.00mm & -2.50mm

Differential Expansion on a turbine is the relative measurement of the rotor'saxial thermal growth with respect to the case.

1515




Key Phasor

A transducer that produces a voltage pulse for each turn of the shaft,called the “Key Phasor signal. It produces a voltage pulse once eachrevolution.

Phase or phase angle, is a measure of the relationship of how one vibrationsignal relates to another vibration signal and is commonly used to calculatethe placement of a balance weight.

This signal is used primarily to measure Shaft rotative speed and serves as a reference for measuring vibration Phase lag angle. The keyphasor transducer is typically a proximity probe. The Keyphasor is a very useful tool when diagnosing machinery problems.

The standard scale factor is 200mV/mil or 7.87mV/um1 mil = 25.4 microns

1616




Rotor Axial Displacement

Radial Movement

Axial Movement

1. Rotor Axial Displacement2. Radial Vibration

XY

FRONTRadial Vibration

1717-2.5mm-1.6mmAway from Probe

+3mm+2.3mmTurbine Differential Expansion; Towards probeXT-61921

25mm20mmTurbine Casing ExpansionXT-61720

180u100uAlternator NDE Bearing 'Y' AxisXT-61519

180u100uAlternator NDE Bearing 'X' AxisXT-61418

180u100uAlternator DE Bearing 'Y' AxisXT-61317

180u100uAlternator DE Bearing 'X' AxisXT-61216

150u100uGear Wheel Bearing 'Y' Axis (Altr)XT-61115

150u100uGear Wheel Bearing 'X' Axis (Altr)XT-61014

150u100uGear Wheel Bearing 'Y' Axis (Tg)XT-60913

150u100uGear Wheel Bearing 'X' Axis (Tg)XT-60812

180u100uGear Box Pinion Bearing 'Y' Axis (Altr)XT-60711

180u100uGear Box Pinion Bearing 'X' Axis (Altr)XT-60610

180u100uGear Box Pinion Bearing 'Y' Axis (Tg)XT-6059

180u100uGear Box Pinion Bearing 'X' Axis (Tg)XT-6048

180u120uRotor Rear Bearing 'Y' AxisXT-6037

180u120uRotor Rear Bearing 'X' AxisXT-6026

180u120uRotor Front Bearing 'Y' AxisXT-6015

180u120uRotor Front Bearing 'X' AxisXT-6004

+/-.8mm+/- .5mmAxial Displacement 'Y' AxisZT-6013

+/- .8mm+/- .5mmAxial Displacement 'X' AxisZT-6002

xxxxxxKey PhaserKPH-1

TripAlarmDESCRIPTION – Vibration Monitor-Bentley NevadaTAG NoSl No

1818




Bearing Temperatures

Temperature of bearings is a measure of the how hot a bearing is operating.It may be due to overloading, misalignment, improper lubricant pressure and/or flow. Nearly all turbine generator bearings were originally installed with bearing temperature sensors. These sensors may be thermocouples orRTDs. Any bearings that was not originally equipped with temperature sensorscan be retro-fitted to accept thermocouples or RTDs.

19199085RTDGEN REAR BRG TEMPORTD21724

9085RTDGEN REAR BRG TEMPORTD21623

9085RTDGEN FRONT BRG TEMPORTD21522

9085RTDGEN FRONT BRG TEMPORTD21421

110100RTDGB WHEEL NDE BRG TEMPORTD20920

110100RTDGB WHEELN DE BRG TEMPORTD20819

120110RTDGB WHEEL DE BRG TEMPORTD20718

120110RTDGB WHEEL DE BRG TEMPORTD20617

110100RTDGB PENION NDE BRG TEMP ORTD20516

110100RTDGB PENION NDE BRG TEMP ORTD20415

110100RTDGB PENION DE BRG TEMP ORTD20314

110100RTDGB PENION DE BRG TEMP ORTD20213

120110T / CTURB BRGTEMP REAROTC21412



120110T / CTURB BRG TEMP FRONTOTC2109



120110T / CTURB THRUST BRG TEMP BTM NEGOTC2066

120110T / CTURB THRUST BRG TEMP TOP NEGOTC2055

120110T / CTURB THRUST BRG TEMP TOP NEGOTC2044

120110T / CTURB THRUST BRG TEMP BTM ACTOTC2023

120110T / CTURB THRUST BRG TEMP TOP ACTOTC2012

120110T / CTURB THRUST BRG TEMP TOP ACTOTC2001

TRIPALARMTYPE

SETPOINTI / O DECRIPTION – Siemens GovernorTAGSR NO

TURBINE TRIP- TEMP

2020



8580RTDHOT AIR TEMP

RTD22710

6050RTDCOLD AIR TEMP

RTD2269

5550RTDCOLD AIR TEMP

RTD2258

8580RTDHOT AIR TEMP

RTD2247

125120RTDALT WINDING TEMP-B PHASE

RTD2236

125120RTDALT WINDING TEMP-Y PHASE

RTD2225

125120RTDALT WINDING TEMP-R PHASE

RTD2214

125120RTDALT WINDING TEMP-B PHASE

RTD2203

125120RTDALT WINDING TEMP-Y PHASE

RTD2192

125120RTDALT WINDING TEMP-R PHASE

RTD2181

TRIPALARMTYPE

SETPOINTI / O DECRIPTIONTAGSR NO

DCS Temperature

2121



Bearing and Winding Temperature

Earth fault Protection

Reverse/Low Forward Power

Over Voltage / Under Voltage

Over Frequency / Under Frequency

Over Current

Differential

Neutral displacement

Negative phase sequence


Generator Protection

22222222



BY

K.R.RAO, AGM (C&I) Power Plants,

Triveni Engineering & Industries Ltd, Noida (UP).

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