EE 4

223/

5223

- Le

ctur

e 41

Wed

nesd

ay A

pril

22, 2

009

Ong

oing

Lis

t of T

opic

s:

•U

RL:

http

://w

ww

.ece

.mtu

.edu

/facu

lty/b

amor

k/E

E52

23/in

dex.

htm

•

Term

Pro

ject

- D

ue F

riday

(rem

ote

stud

ents

can

neg

otia

te e

xten

sion

)•

Loca

l pre

sent

atio

ns: 1

2:45

- 2:

45pm

Wed

; EE

RC

B45

•G

en P

rote

ctio

n - C

h. 8

, Bas

ic P

rote

ctio

n is

sues

(sum

mar

y fro

m p

rev

lect

ures

)•

IEE

E P

ublic

atio

n 95

TP10

2 - P

rot o

f Syn

ch G

ens

•IE

EE

C37

.102

- G

uide

for A

C G

ener

ator

Pro

tect

ion

•IE

EE

C37

.101

, C37

.106

- G

roun

d P

rote

ctio

n, A

bnor

mal

Fre

q P

rote

ctio

n•

Gro

undi

ng Is

sues

•N

otes

from

adj

unct

facu

lty, e

xam

ple

•O

ut-o

f-ste

p is

sues

- se

e al

so K

undu

r’s te

xt•

An

extre

me

exam

ple

of s

tray

volta

ge (n

eutra

l cur

rent

retu

rn th

ru g

nd p

aths

) •

Mot

or P

rote

ctio

n •

Arm

atur

e - s

imila

r stra

tegi

es a

s w

ith S

ynch

Mac

hine

s•

Bea

ring

Tem

p, v

ibra

tion

•O

ther

issu

es -

See

Ch.

11•

SC

AD

A b

asic

s, tr

ansd

ucer

s, s

calin

g fa

ctor

s fo

r rel

ays

and

SC

AD

AN

ext/L

ast:

•B

asic

DS

P re

lay

algo

rithm

s –

conv

ert s

ampl

es w

avef

orm

s in

to p

haso

r Vs

and

Is•

Rea

l-tim

e C

omm

unic

atio

ns fo

r pro

tect

ion

& c

ontro

l, IE

C 6

1850

2

The SEL-710 Motor Protection Relay takes the next logical step in motor monitoring and control. While other motor relays assume a constant value for rotor resistance, the SEL-710 dynamically calculates motor slip and uses this information to precisely track motor temperature using the AccuTrack Thermal Model. Rotor resistance changes depending on slip and generates heat, especially during starting, when current and slip are highest. If your motor protection uses a constant rotor resistance for thermal protection, it could be off by a factor of three or more. By correctly calculating rotor temperature, the AccuTrack Thermal Model reduces the time between starts. It also gives the motor more time to reach its rated speed before tripping.

Functional Overview

AccuTrack™ Thermal Model

Saved Cooling Time

I2t Relay

SEL-710

Rotor Temperature

Motor Current

Rotor Resistance

Tem

pera

ture

(per

uni

t of l

imit)

0

0.1

0.2

0.3

0.5

0.6

0.8

0.9

1.0

0.7

Curr

ent

0.4

0

1

2

3

5

6

8

9

10

7

4

0 2 4 6 8 10 12 14 16 18 20

Seconds

Accurate thermal modeling provides protection that maximizes motor availability while providing excellent protection from damage.

87

* Optional Functions

** Select When Ordering

• Sequential Events Recorder

• Event Reports, Motor Start Reports, Motor Operating Statistics, Load Profiles, and Motor Start Trends

• SEL ASCII, Ethernet*, Modbus® TCP, IEC 61850*, Modbus RTU, Telnet, FTP, and DeviceNet™* Communications

• Front-Panel LED Programmable Targets

• Two Inputs and Three Outputs Standard

• I/O Expansion*—Additional Contact Inputs, Contact Outputs, Analog Inputs, Analog Outputs, and RTD Inputs

• Single or Dual Ethernet, Copper or Fiber-Optic Communications Port*

• Battery-Backed Clock, IRIG-B Time Synchronization**

• Instantaneous Metering

• Programmable Front Pushbuttons and LED Indicators

• Forward/Reverse Start Protection

• Advanced SELOGIC® Control Equations

• 32 Programmable Display Messages

• MIRRORED BITS® Communications

• Low-Voltage Starting

• Two-Speed Motor Protection

37 47

PhaseReversal

LC/71

UndercurrentUnderpower*

46

CurrentUnbalance

LoadJam

Load Jam

66

Starts-Per-HourTime Between

Starts

49

Motor ThermalOverload

59

Overvoltage

55

Power Factor

VAR

Reactive Power

60

Loss-of-Potential

27

Undervoltage

Overcurrent • Phase • Residual • Neg. Seq.

50PGQ

81 OU

Load Control • Percent TCU • Current • Power*

Frequency • Over • Under

50N

Neutral Overcurrent

38

BearingTemperature

49R

49P

Temp., Alarm,and Trip

14 SpeedSwitch

PTC Thermistor**

SEL-710 Motor Protection Relay

RTD Inputs*

LoadMotor

3,2,1

1

3

Voltage Input*

Internal* or External* RTD Inputs

PTC Overtemperature

Current Differential

NEW

NEW

NEW