Motor Sony

RELAY SETTING FOR MOTOR

VOLTECH ENGINEERS PVT.LTD.

PROJECT: 2 x 150 MW COAL BASED THERMAL PROJECT, THOOTHUKKUDI

TITLE: RELAY SETTING FOR 6.6KV MOTOR

CLIENT : IND BARATH THERMAL POWER LIMITED

DATE/REV 12.06.12/0

6.6kV Unit Service Switch Board ,

1700KW ID FAN

INPUT DETAILS:-

I. CT Detailsa. CT Ratio=250/1Ab. CT Primary=250Ac. CT Secondary=1A

II. Motor Details a. Output(Pnm)=1700KWb. Rated voltage(Unm)= 6600Vc. Motor FLC(Inm) = 183.9A

d. LRC-pu = 6.5Timese. LRC-Amps =1195.0Af. Motor Starting time =5sec

g. No load Current=24Ah. No load Starting Time =5 Sec

i. Locked rotor withstand timea. Hot Start=2b. Cold start=3

j. Starting Method/Coupling=DOLIII. Relay Details

a. Relay Type = P220b. Make = ALSTOM

A. RELAY SETTING:-1) THERMAL OVER LOAD

PROTECTION(49)Note: Refer Thermal limitation, current-time curve

1.1)Threshold = Iθ Motor FLC(In)=184A

Iθ = [(FLC X1.05)/CTR]*1.2Iθ =[(183.9x1.05)/250]*1.2Iθ=0.93*In

Relay thermal overload characteristics shall be below the motor hot & cold thermal withstand characteristics. Based on the motor characteristics we have chosen.

1.2) Hot & Cold Curve Setting: a. Heating time constant as

=13b. Cooling time constant =15

Trip time characteristics t=T ln [(K^2 - θi) /(K^2-θthresh)]

where,t = operating time in secondsT = thermal time constant value in secondsIeq = equivalent thermal current valueIθ> = thermal overload current thresholdK = Ieq / Iθ> ratioθi = initial thermal state value ; (in our case θi equal to 0)θthresh = alarm threshold (settable) or tripping threshold (fixed value equal to 1)

So, above formula rewritten as,t = T ln [(K^2)/(K^2 - 1)]

a. Is Heating Time constant within safe?

i. At 500% of FLC Load current taken=500% of FLC

Trip time =0.60min(35.85sec)

ii. At 400% of FLC Load current taken= 400% of FLC Trip time =0.94min(56.51sec)

iii. At 300% of FLC Load current taken=300% of FLC Trip time =1.73min(103.74sec)

iv. At 200% of FLC Load current taken=200% of FLC Trip time =4.22min(253.00sec)

Hence the chosen Heating Time constant 13 is below the motor thermal curve (hot).

b.Is Cooling Time constant within safe? Cooling time constant =15

i. At 500% of FLC Load current taken=500% of FLC

Trip time = 0.69min(41.37sec)

ii. At 400% of FLC Load current taken= 400% of FLC

Trip Time =1.09min(65.20sec)

iii.At 300% of FLC Load current taken=300% of FLC Trip Time =1.99min(119.70sec)

iv.At 200% of FLC Load current taken=200% of FLC Trip Time =4.87min (291.92sec)

Hence the chosen cooling Time constant 15 is below the motor thermal curve (cold).

1.3Themal Alarm Threshold (θ Alarm)

= (FLC)/(Threshold Iθ)

= 183.9/194

= 0.95=95 %

1.4Forbid Start :

θforbid start < [(Id / Iθ>)2 * (1 �exp(td / Te2))] + exp (td / Te2)

Where: Id = actual start-up current, td = actual start-up time, Te2 = thermal time-constant at the

moment of start-up,

Iθ> = current threshold of thermal overload,

ttrip = time of tripping for the thermal replica protection

= θforbid start < [(Id / Iθ>)2 * (1 exp(td / Te2))] + exp (td / Te2)�

=(1195/194)^2x(1exp(10/10))+exp(10/10)

=0.69 = 69

2 SHORT CIRCUIT PROTECTION(50/51)

Motor starting current,IS =1195 A

130% of Motor Start Up current= 1553.5 A

= 1553.5*(1/250)

Current threshold I>> = 6.20In

Time-delays tl>> = 0.10 s

3 EARTH FAULT PROCTION(50/51)=

Relay rated current,In = 1 A

20% of relay rated current is considered, = 0.2*1

Current thresholds lo> = 0.2A

Time-delays tlo> 0 s

For lo>> Setting to 6% of Max. Earth fault

Current thresholds lo>> =1.2A

Time-delays tlo>> = 0.1s

4 UNBALANCE PROTECTION (46)

Threshold li> = 10% of FLC of Motor

CT Ratio

= 0.1x183.9

250

= 0.074 In

Time-delays tli> = 10 Sec

Threshold li>> = 20% of FLC of Motor

CT Ratio

= 0.2x183.9

250

= 0.147 In

5 EXCESS LONG START UP PROTECTION (48)

Threshold I start = Id= Starting Current X Motor Current In→ I Start =2*Iθ

= 1195

Here Motor start-up current is higher than 6 times the rated current so

recommended setting is 3Iθ3Iθ

* Typical settings are :

• [Istart] is equal to:

⇒ 1.5*[Iθ>] if the motor start-up current is lower than 4 times the rated current;

⇒ 2*[Iθ>] if the motor start-up current is equal to or higher than 4 times the rated current and lower than 8 times the rated current;

⇒ 3*[Iθ>] if the motor start-up current is equal to or higher than 8 times the rated current.

tIstart = 1.2xtdSec

here td is Start up time

= 6 Sec

6 BLOCKED ROTOR PROTECTION (51LR/50S)

Threshold I stall = Id= Starting Current X Motor Current In→ I Start =2*Iθ

= 1195

Here Motor start-up current is higher than 6 times the rated current so recommended setting is 3Iθ

3Iθ

Type of Motor = ID FAN

tIstall = 1.7Sec

* Typical settings are :

• [Istart] is equal to:

⇒ 1.5*[Iθ>] if the motor start-up current is lower than 4 times the rated current;

⇒ 2*[Iθ>] if the motor start-up current is equal to or higher than 4 times the rated current and lower than 8 times the

rated current;

⇒ 3*[Iθ>] if the motor start-up current is equal to or higher than 8 times the rated current.

[tIstall] is 1 to 2 s for a pump and a fan, and 5 to 10 s for a crusher. In all the cases, this setting must be lower than the withstand time for the motor with the rotor stalled.

7 LOSS OF LOAD (OR) UNDER CURRENTPROTECTION (37)

Threshold I< = No load currentIt must be higher than No load

current

CT Ratio

= 24

250

= 0.096 In

tl< = This setting depends on the load driven by the motor (often set to a few seconds).

= 3 Sec

Tinhib = " This setting depends on the load connected to the motor. If the motor is

started on load , this delay time is set to its minimal value, that is to say 0,05 s. Ifthe motor is idle-started, this delay time

is set to be slightly longer than the load increase time of the motor."

= tl<+No load Stating Time

= 8 Sec

THERMAL OVER LOAD PROTECTION(49)

Sub Menu Primary SettingSecondary Setting Setting range

Thermal overload function enabled ?Yes

Thermal inhibition on start enabled ?No

Threshold Iθ> 194 A 0.930.2 to 1.5 In by steps of 0.01 In

Ke 3 0 to 10 by steps of 1

Te1 13 1 to 180 min by steps of 1 min

Te2 10 1 to 360 min by steps of 1 min

Tr 15 1 to 999 min by steps of 1 min

Influence RTD (optionalN

θALARM enabled? Yes

Thermal alarm threshold θALARM95 Set to 100%

θ FORBID START enabled ?Y

FORBID START 69 20 to 100% by steps of 1%

SHORT CIRCUIT PROTECTION(50/51)


Short-circuit function enabled ?Yes

Threshold I>> 1195 A 6.21 to 12 In by steps of 0.1 In

tI>> 0.10 0 to 100 s by steps of 0.01 s

EARTH FAULT PROCTION(50/51)


"Earth fault function enabled ?:

threshold Io>" No

Thresholds Io> 0.20.002 to 1 Ion by steps of 0.001

tIo> 0.00 0 to 100 s by steps of 0.01 s

"Earth fault function enabled ?:

threshold Io>>" Yes

Threshold Io>> 1.200.002 to 1 Ion by steps of 0.001

tIo>> 0.10 0 to 100 s by steps of 0.01 s

UNBALANCE PROTECTION (46)


"Function Unbalance enabled ?:

threshold Ii>" Yes Alarm threshold enabled

Threshold Ii> 0.10.05 to 0.8 In by steps of 0.025 In

tli> 18 A 10 0.04 to 200 s by steps of 0.01 s

"Function Unbalance enabled ?:

threshold Ii>>" YesTripping threshold enabled

Threshold Ii>> 37 A 0.150.2 to 0.8 In by steps of 0.05 In

EXCESS LONG START UP PROTECTION (48)


"Excess long start function

enabled ?" YES

Threshold Istart 582 A 3Iθ1 to 5 Iθ by steps of 0.5 Iθ

tIstart 6 1 to 200 s by steps of 1 s

BLOCKED ROTOR PROTECTION (51LR/50S)


Block rotor function enabled ?YES

tIstall 1.70.1 à 60 s by steps of 0.1 s

"Stalled-in-run rotor function

enabled ?" YES

Threshold Istall 582 A 3Iθ1 à 5 Iθ by steps of 0,5Iθ

"Blocked-at-start rotor function

enabled ?" YES

LOSS OF LOAD (OR) UNDER CURRENTPROTECTION (37)


Loss of load function enabled ?YES

Threshold I< 24 A 0.10 0.1 to 1 In by steps of 0.01 In

tI< 3 0.2 to 100 s by steps of 0.1 s

Tinhib 8 0.05 to 300 s by steps of 0.1 s

Reference Documents:

1. Motor Data Sheet

2. Single line Diagram for 6.6kV Switch board

3. MiCOM-P220_TechnicalGuide-EN

4.MiCOM -P220 Relay cataloge

5. Motor Characterstics Curve Graphs

Motor Sony

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