CONTROL OF SYNCHRONOUS MACHINE BY USING DIGITAL MOTOR

PROTECTION RELAY

PROJECT TITLE :

Oxygen gas plays a vital role in steel making process for that purpose oxygen compressors are used. To drive this compressors 11MW/11KV synchronous motors are used. To protect this motors relays are used.

The protection usually provide for three phase motors, while generally effective against overload and short circuit conditions rarely taken in to full account the harmful effects of unbalanced line currents.

The motor protection relay measure the load current and unbalanced current independently, and provide accurate protection against thermal damage under all operating condition.

Earlier electro magnetic relays are failed to give complete fault record and history on protection parameters.

ABSTRACT:

General Features Of VSP:

VSP is the only shore board integrated steel plant in our

country

VSP is the home for several hurry industry in public

sectors like BHPV, Hindustan shipyard, HPCL etc.

VSP contains the following sections: Coke oven and coke chemical plant

Sinter plant

Blast furnace

Steel melting shop

Thermal power plant

Air Separation Plant

In ASP air is compressed to 6.4 Kscg(kg/cm)

This air is pre cooled in air water to 100c

This is air is passed through the main exchanger where it is cooled to its due point and from the exchangers will be sent to distillation column which would separate the air in to oxygen nitrogen and argon.

Not only the gaseous products liquid products such as liquid oxygen, liquid nitrogen, liquid argon are also produced.

SMS required 99.5% of oxygen for LD converter blowing

64.47% of total nitrogen for blast furnace

Synchronous Motor

Induction motor have fixed stator winding that are electrically connected to AC power

In case of synchronous motor have fixed stator winding electrically connected to the AC supply with separate source of excitation

Induction motor can be started by applying AC power to the stator winding. But synchronous motor required special attention to start because initially synchronous motor acts as a induction motor

when the synchronous motor is running at synchronous speed it is possible to alter the PF by varying the excitation to the rotor field

Synchronous motor protection

Figure highlights multiple functions used to monitor the status of the synchronous motor.

These devices includes field over and under current, motor pullout protection and incomplete sequence.

As the synchronous motor builts to rated speed some maximum time is defined by the manufacture for the excitation to be applied.

If motor takes longer than the defined time, rotor squirrel cage winding will over heat.

Then the relay is set to trip the motor in time to protect the squirrel cage winding.

The lagging phase angles occurs when insufficient excitation fails to provide the needed synchronising torque.

The field under current relay monitors for insufficient field current from the excitation.

Leading and Lagging Current as Affected by

Field Excitation on the Synchronous Motor

CTMM Relay

I2 conscious Thermal Protection. Selectable Thermal Characteristics Built-in Stalling protection with provision for external control.feed with instantaneous or time-delayed operation option Sensitive earth fault protection suitable for either residual or CBCT

Features:

.

Pre-trip alarm with adjustable pick up and time delay with LED Indication.. Auxiliary supply supervision with Alarm & LED indication.Built-in Load IndicatorSuitable for AC or DC Aux. Supplies.

Typical static motor protection relay front facia

Motor characteristics must be carefully considered when applying protection.

The protection usually provided for three phase motors while generally effective against loads and short circuit conditions.

motor protection relay type CTMM & CTMFM measure the load current and unbalanced current independently and provide accurate protection against thermal damage under all operating conditions.

APPLICATION OF CTMM RELAY:

DIGITAL MOTOR PROTECTION RELAY

MICOM P220 TYPE

FEATURES:Digital motor protection relay has continuous range.It has a possibility of recording of fault.It can give the complete protection.It has also external features.It has a time delay function.

The motor protection relay range is designed for motor protection application .

A complete set of protection function is performed on the measurement of current ,voltage and temperature.

On top of that high inertia loads and anti- backspin protection ensures that the rotor stops the motor can be re started

Application:The MiCOM P220 Protection Relay range performs and offers a numerous function in a compact design:Protection Monitoring Diagnosis Fault analysis toolsAid to maintenance

Compact and* plug and play* made*, the p220protection relay range supply essential functions fox industry applications. Where the following requirements must be achieved:Small and medium motors High inertia CompactEasy to use Low cost

FUNCTIONAL DIAGRAM

Protection function is autonomous and can be individually configured or disables to suit a particular application

Protection functions

Short-circuit (50/51)

Earth fault (50N/51N)

second motor protection modemotor(48/49/49LR50S/66)

CB failure (50BF)

Limitation of the number of starts, timbetweenstarts(66)

Loss of load (37)

Unbalance, loss of phase and single phasing (46)

Thermal overload (49)-true RMS value

Locked rotor while running or at start-up (51s)

CONTROL FUNCTIONS

Independent protection setting groups

Programmable scheme logic

Trip circuit super vision

CB monitoring

External trips

Shape of start up current and voltage

Analog outputs

Trip cause statistics

Measurement and recording facilities

The relay constantly measures a large amount of electrical data such as

Phase current magnitude in true R.M.S value :IA,IB,IC.

Neutral current magnitude in true RMS value IN.

Positive sequence current I1, negative sequence current I2, zero sequence current I0 & unbalance ratio I1/I2

Frequency, peak current value, phase to phase voltage true RMS value, active & Reactive power W&VAR., Active &Reactive energies Wh & VARh and power factor.

User interface

Front plate and menus Dedicated and programmable LEDs

Local and remote communication

Software support

MiCOM S1 Software makes it possible to pre-set all MiCOM P220 relay parameters from a PC. The relay is then accessed via the RS232 port on the front panel.

Complete configuration of the micomp220

It can be completely configured either by using interface or by using the control and setting software MICOM S1.

Thermal overload

Short circuit

Earth fault

Unbalance

Excess long start

Blocked rotor

Loss of load

RTD (optional)

Protection functions Thermal replica

Thermal current threshold

Over load time constant TE1

Short circuit protection

Unbalance protection

Too long start up protection

Locked raptor protection

Under current protection

RTD temperature detection or thermostats

AUTOMATION FUNCTIONS

Limitation of the number of start- ups

Time between 2 start-ups

Logic inputs /auxiliary timers

Logic equations time delay

Auxiliary output relay

Latching of the output relays

Trip output relay

Control and monitoring of the breaker device

Optional functions

Recording functionsEvent recorder

Fault recorder

Inputs and outputs

Phase current IIN 1 and 5 amp

Earth current Ion 1 and 5 amp

Frequency range 45 to 65 Hz

nominal 50/60Hz

Burdens phase current inputs <0.3 VA (5A)

<0.2 VA (1A)

earth current input <0.001 VA at 0.1 I ON

.

THERMAL OVERLOAD CHARECTERISTICS

CONFIGURATION OF THE RELAY AND PC

•Once the physical connection is established, the relay and pc settings must be checked in order to start the communication.

HUMAN MACHINE INTERFACE OUTPUT PARAMETERS

PASSWORD=****

TYPE=P220

REFERENCE=XXXX

SOFTWARE VFR=3C

FREQUENCY =50 Hz

ACTIVE GROUP=1

INPUT ST=00000

OUTPUT ST=0000

DATE,TIME.

CONCLUSION:• The motor protection relay range particularly adopted to oil refinery glass and cement manufacturing paper mills and mining etc.

• so the P220 relay can nevertheless be used as a multi function relay to protect a high power synchronous motor.

• Digital motor protection relay has got very handsome computing power, as it incorporates a microprocessor with it.

• Present digital relays give all the protection features of old electro mechanical or static relays. In addition it gives communication facia supervision and add trouble shooting features on it.

• so it has become versatile productive cum human machine interface module.