A55-76-it

MarelliMotori

ASI.CT.035.4 GB

IIC

D5, D6 SERIES

II 2GEx d/de IIC

Motors forHazardous Areas

NEW

D6SERIES

ASI.CT.035.4 GB

This catalogue refers to ATEX Motors belonging to Group II Category 2G as described.

STANDARDS

(*) Limit +60°C for temperature class T3 only. The minimum ambient temperature for Ex d protection is –50°C (heating required before starting the motor).

Temperature Limits

-20°C +60°C*

-20°C +60°C*

Number

BVI 08 ATEX 0001

CESI 03 ATEX 134

Frame size

71-132

160-315

CERTIFICATES

(*) Terminal box casted with frame for Ex d execution

MATERIALS

71-80Size (mm)

Protection Mode

Frame

Frame endshields

Fan cowl

Fan

Terminal Box

Ex d - Ex de

Cast Iron

The ATEX Motors described in this catalogue are manufactured in accordance with IEC 60034-1-5-6-7-8-9-12-14, IEC 60072-1, EN 50347, EN 60079-

0-1-7.

GROUPS

The electrical motors are subdivided into two groups,depending on the environment they are meant for:

DescriptionGROUPequipment used in mines and on the surface of minesequipment used in explosive atmosphere other than mines (surface industries)

I

I I

TYPES OF PROTECTION

The types of protection are defined as follows:G A S e n v i r o n m e n ts

P R OT E C T I O N The equipment must be designed in such a way that:

• no internal explosion can be spread to the surrounding explosive atmosphere

• no sparks, arcs, or hot spots can occur in service, including starting and locked

rotor situation, in all internal and external parts of the machine

• an “Ex d” flameproof enclosure is combined with the terminal box featuringan “Ex e” increased safety protection

E x d

E x e

E x d e

GROUP (IIA, IIB, IIC)Gas atmospheres are furtherly divided into 3 sub-groups (IIA. IIB and IIC), according to the severity of the environment. This catalogue refers to motors belonging togroup IIC, which are suitable for medium-danger environment (some examples of IIC atmosphere are: hydrogen, acetylene, water gas, carbon sulphur).

Equipment and protective system intended for use in potentially explosive atmospheres (ATEX) 94/9/ECElectromagnetic Compatibility (EMC) 2004/108/IECLow Voltage Directive (LVD) 2006/95/ECMachinery Directive (MD) 98/37/EC

EUROPEAN DIRECTIVES

Title Directive

D

SAFE

Zone 22

Zone 21

Zone 20

G Zone 2

3G

3GD

2GD

2G

2GD

2GD

SAFE

Standard

Industrial

3D

2D

MOTORS NOT PERMITTED

EQUIPMENT AND AREAS CLASSIFICATIONS

The table on the right defines the EQUIPMENT CATEGORY suitable for each CLASSIFIED AREA. Dangerousenvironments are classified by ZONE, according to the risk generated by explosive GAS (zone 0, 1 and 2) orDUST (zone 20, 21 and 22). The equipment is classified by CATEGORY according to the level of protection theapparatus must have (specified by a number) and the atmosphere in which it will operate (specified by theletter G, D or GD). In the areas and equipment classification lower numbers stand for higher danger andrequirement for higher protection. In zone 0/20 the use of electric motors is not allowed.

Zone 1 Zone 0

The data sheets included in this catalogue referto the series shown in this table.

NOMENCLATURE

90-132 160 180-225 250-315

Cast Iron

Steel

Steel

Steel

Thermoplastic

Cast Iron*

Frame sizewhere

applicable

71 - 132

160 - 315

Temperature ClassGroupProtection

Ex d

Ex de

CategoryGroup

II

II

Series

D6K

D6Y

D5K

D5Y

Ex

2G

2GEx d

Ex de

II C

II C

T3–T4–T5

T3–T4–T5

T3–T4

T3–T4

ASI.CT.035.4 GB

254

279

318

406

356

D5_160

D5_180

D5_200

D5_250

D5_225

M

L

M

L

L

S

M

M

L

E

D

AC

C B

BB

HA

A

AB

K

H

HD

T

M

P N D

LA

L

E

S

LD

IM B5 (IM 3001) IM V1 (IM 3011)

P N D

E

L

T LA

M

S

IM B14 (IM 3601)

IM B3 (IM 1001)Frame size 160-400

2 - 8

2 - 8

2 - 4

4 - 8

2 - 8

4 - 8

2

4 - 8

2

4 - 8

A

FRAME SIZE

2 - 8

2 - 8

2 - 8

2 - 8

2 - 8

2 - 8

2 - 8

2 - 8

IEC POLES

71

80

90

100

112

132

112

125

140

160

190

216

A

M

M

S

L

L

M

S

M

29

31

34

36

40

45

AA

T4

2,93,2

3,33,9

3,3

2,62,8

2,83,1

2,93,7

3,1

0,000480,00048

0,000920,00092

0,001750,00175

0,0037

1818

2323

3535

53

5,65,8

6,26,4

7,37,5

7,7

71 MA271 MB2

80 MA280 MB2

28402840

28602870

75,476,8

79,680,9

84,6

0,810,81

0,800,81

0,840,86

0,89

0,91,3

1,72,4

3,14,4

5,8

1,241,85

2,503,66

4,997,32

9,95

Ex d IIC, Ex de IIC

D6•D6•

D6•D6•

All rated values refer to: Ambient Temperature 40°C, Installation 1000 m a.s.l, Insulation cl. F, duty S1.

PERFORMANCE AT RATED OUTPUT

MOMENTOF INERTIA

WEIGHTIM 1001

RATEDOUTPUT

MOTOR TYPE

J

[kgm2]

Approx.BREAKDOWNTORQUE

TMAX / Tn

p.u.p.u. p.u.

Ts / Tn

SPEED EFFICIENCY

RATEDCURRENT

I

[A]

RATEDTORQUE

Tn

POWERFACTOR

COS

PERFORMANCE AT RATED VOLTAGE

STARTINGCURRENT

STARTINGTORQUE

Is / In

400V 50Hz

50 Hz SERIES FRAMESIZE

[kW] [rpm]

[Nm]

[kg][%]

2 poles = 3000 rpm

Is = Starting current, Ts = Starting torque, TMAX = Breakdown torque.Detailed data for 440V/60Hz on request.Higher output available for Temperature Class T3 and/or Maximum Surface Temperature T150°C.Motor not multivoltage. Output values at 440V/60Hz refer to motors with dedicated winding.

D6•

D5•

• = K for 2G Ex d IIC

• = Y for 2G Ex de IICSERIES SELECTION

50 Hz

225 M2

315 SM2315 MA2315 MC2315 MD2

D5•D5•D5•D5•

292029202928

292029252925

29452945

2975297029752980

87,988,889,1

86,5

88,489,890,0

92,092,2

94,394,394,494,7

0,890,900,90

0,820,830,81

0,870,87

0,870,860,870,87

10,213,616,2

21,929,036,7

5467

194235281351

18,024,529,4

364960

97120

353424513640

7,27,27,3

6,26,46,8

6,76,9

6,46,56,56,5

2,72,72,9

2,22,22,3

2,32,4

2,42,52,52,5

2,92,93,0

2,83,03,0

2,93,0

2,42,52,52,5

0,01710,01710,0171

0,0300,0350,040

0,1650,180

0,950,951,121,30

999999

155160165

250260

1050105011151195

132 SA2132 SB2132 MB2

160 MA2160 MB2160 L2

200 LA2200 LB2

D6•D6•D6•

D5•D5•D5•

D5•D5•

--

90 S290 L2

D6•D6•

100 LA2D6•

112 M2D6•

180 M2

250 M2D5•

280 S2280 M2

D5•D5•

28702870

2880

2890

2960

29602960

82,683,8

93,694,2

0,870,88

133157

242290

6,87,2

2,32,3

93,0 0,87 98 177 6,7 2,4

0,90 7,4 13,2 7,5 2,7 2,9

2,72,7

0,3500,416

575630

3,0 0,250 360

0,0060 62

0,370,55

0,751,1

11,015,018,5

30,037,0

5,57,59

110132160200

1,52,2

3

4

55,0

75,090,0

22,0

45,0

D5•

D5•

90,52930 0,84 41,8 72 6,8 2,4

2960 92,5 0,88 80 145 6,6 2,4 3,0 0,225 320

3,0 0,048 188

ASI.CT.035.4 GB

18 5

324466

488

508

300

465

406

411

314

354

349

210

254

241

279

305

286

311

168

108

149

121

133

160

250

225

180

200

22

28

24

446

618

593

22

14

18

406

296

283

321

350

360

648

723

830

800

830

710

790

895

140

140

110

110

42

48

60

55

60

55

300

350

500

400

250

300

450

350

350

400

550

450

18

16

15

18368

65

S

FLANGE B5 - V1 FLANGE B14

AB AC B C H HA HD KBB L LD E M N P LA S T M N P TAD

178

120

150

184

159

187

195

246

208

CA D

14

19

24

38

28

M6

M8

S

FLANGE B5 FLANGE B14

138

156

172

196

225

255

AB

146

166

386

AC

63

70

45

50

56

89

C

71

80

90

100

112

132

H

15

8

10

12

13

HA HD

12

7

10

K

172

112

126

214

BB

280

335

L LD

30

40

50

80

60

E

130

165

265

215

M

110

130

230

180

N

160

200

300

250

P

10

7

14

LA

12

10

14,5

S

3,5

4

T

85

100

115

130

M

70

80

95

110

N

105

120

140

160

P

2,5

3,5

3

TAD

90

100

125

140

BA

13,5

16

11

13

18

BC

315

380

LC W

131

141

160

205

175

30

40

50

80

60

EADA

14

19

24

38

28

5

6

8

10

F

5

6

8

10

FA

16

21,5

27

41

31

GA

16

21,5

27

41

31

GC

215

226

119

133

208

241

Ex d Ex e

190

213

298

315

338

373

Ex d Ex e

184

204

228

275

286

179

193

268

301

152

176

199

284

301

324

359

385

445

460

550

440

510

525

635

295

350

400

460

475

565 165 130 200 M10

SHAFT EXTENSIONDIMENSIONS

D

140

T4

2,52,5

3,03,2

2,92,9

2,52,6

2,72,7

3,03,2

2,82,7

0,000970,00097

0,002450,00245

0,00340,0034

0,00750,0075

1919

2424

3636

5656

4,24,4

5,95,9

6,16,2

5,95,9

71 MA471 MB4

80 MA480 MB4

0,250,37

0,550,75

14101410

14101420

68,671,0

72,073,7

84,284,4

0,650,68

0,800,81

0,790,81

0,820,81

0,81,1

1,41,8

2,63,4

4,66,3

1,692,51

3,725,04

7,4010,1

14,619,9

Ex d IIC, Ex de IIC

D6•D6•

D6•D6•



MOMENTOF INERTIA

WEIGHTIM 1001

RATEDOUTPUT

MOTOR TYPE

J

[kgm2]


TMAX / Tn

p.u.p.u. p.u.

Ts / Tn

SPEED EFFICIENCY

RATEDCURRENT

I

[A]

RATEDTORQUE

Tn

POWERFACTOR

COS


STARTINGCURRENT

STARTINGTORQUE

Is / In

400V 50Hz


[kW] [rpm]

[Nm]

[kg][%]

4 poles = 1500 rpm


D6•

D5•



50 Hz

225 S4225 M4

315 SM4315 MA4315 MC4315 MD4

D5•D5•D5•D5•

11,015,0

30,0

14501450

14551460

1470

14751475

1488148514851485

87,988,2

85,7

88,6089,40

91,60

92,5092,50

93,6094,5094,8095,30

0,820,82

0,810,81

0,84

0,860,86

0,850,850,850,86

11,015,0

22,1029,90

36,2041,80

56

6782

200237287353

36,249,4

7298

121143

195

239291

70584810281285

6,26,3

5,25,8

6,26,3

6,4

6,56,5

6,56,56,26,5

2,52,6

2,02,2

2,32,4

2,4

2,32,4

2,62,52,52,5

2,62,8

2,12,4

2,8

2,82,8

2,62,52,52,6

0,0320,032

0,0340,075

0,0900,110

0,180

0,3200,410

2,102,102,503,10

101101

165182

190240

270

325342

1080108012101370

132 SA4132 MA4

160 M4160 L4

200 L4

D6•D6•

D5•D5•

D5•

D5•D5•

5,57,5

18,5022,0

37,045,0

110132160200

2,02,0

90 S490 L4

D6•D6•

100 LA4100 LB4

D6•D6•

112 M4D6•

180 M4180 L4

250 M4D5•

280 S4280 M4

D5•D5•

D5•D5•

1,11,5

2,23

4

55,0

75,090,0

14201420

14401440

1445

14601465

1475

14801480

78,279,3

90,090,50

0,820,84

93,7093,90

0,860,88

134157

483580

7,07,1

2,52,7

93,0 0,87 98 356 6,4 2,3

0,82 8,2 26,4 6,8 2,8 3,0

2,52,5

2,32,4

0,8851,060

608665

2,6 0,520 410

0,0125 68

T4

2,32,4

1,9

1,6

2,32,42,5

2,02,0

2,12,3

2,0

1,5

2,02,01,9

0,00290,0029

0,00370,0037

0,0075

0,0125

0,0390,0390,039

2525

4242

56

71

106106106

3,73,9

4,04,2

3,8

4,0

4,54,64,6

80 MA680 MB6

90 S690 L6

100 LA6

112 M6

132 SA6132 MA6132 MB6

0,370,55

0,751,1

930930

920920

940

950950960

64,566,9

66,769,9

76,6

80,3

84,785,085,4

0,600,69

0,720,74

0,77

0,77

0,750,750,76

1,41,7

2,33,1

3,7

5,1

6,89,1

12,2

3,85,6

7,811,4

15,4

22,3

30,240,254,7

Ex d IIC, Ex de IIC

D6•D6•

D6•D6•

D6•

D6•D6•D6•



MOMENTOF INERTIA

WEIGHTIM 1001

RATEDOUTPUT

MOTOR TYPE

J

[kgm2]


TMAX / Tn

p.u.p.u. p.u.

Ts / Tn

SPEED EFFICIENCY

RATEDCURRENT

I

[A]

RATEDTORQUE

Tn

POWERFACTOR

COS


STARTINGCURRENT

STARTINGTORQUE

Is / In

400V 50Hz


[kW] [rpm]

[Nm]

[kg][%]

6 poles = 1000 rpm


D6•

D5•



50 Hz

180 L6

225 M6

280 S6280 M6

315 SM6315 MA6315 MB6315 MC6315 MD6

D5•D5•D5•D5•D5•

1,5

34,

5,5

15,0

18,5022,0

37,0

965967

970

970972

975

975

980980

985985985985985

86,088,0

88,2

88,289,0

90,5

91,0

92,593,0

94,094,094,093,394,8

0,820,82

0,82

0,830,83

0,84

0,84

0,840,83

0,830,850,840,850,86

15,422,0

30,0

36,543

58

70

85103

136163199238253

74108

147

182216

294

362

440535

730872106512781385

5,05,5

5,2

5,25,5

6,2

6,5

6,06,0

6,36,06,06,36,3

2,22,3

2,3

2,12,4

2,4

2,6

2,52,5

2,62,52,52,52,7

2,32,5

2,2

2,32,4

2,4

2,6

2,52,5

2,62,52,52,52,5

0,0870,110

0,130

0,1700,220

0,470

0,570

0,8501,075

2,602,603,003,604,40

175182

231

250270

330

400

560665

10001000107011801310

160 M6160L6

200 LA6200 LB6

250 M6

D5•D5•

D6•

D5•

D5•D5•

D5•

D5•

D5•D5•

2,2

7,5011,0

30,0

45,055,0

75,090,0110132143

930

1,81,9

ASI.CT.035.4 GB

BB

480

520

A

457

508

C

190

216

H

280

315

HA

40

45

HD

710

820

K

22

27

L

960

1102

1132

1102

1132

1102

1132

LD

1045

1177

1207

1177

1207

1177

1207

D65

75

65

75

65

80

65

80

70

90

M

500

600

N

450

550

P

550

660

LA

18

22

S

18

22

T

5

6

B

368

419

457

AB

540

590

AC

490

604

DIMENSIONS

FRAME SIZE

2

4 - 8

2

4 - 8

2

4 - 8

2

4 - 8

2

4 - 8

IEC POLES

D5_280

D5_315

S

M

SM

SM

MA

MA-MC

MD

MD-ME

FLANGE B5 V1

E

170

140

170

140

170

140

T4

--

2,02,1

1,91,8

1,7

1,71,6

1,91,9

2,02,0

1,51,4

1,2

1,51,4

0,00290,0029

0,00370,0037

0,00750,0075

0,0132

0,0390,039

2525

4242

5656

71

106106

2,62,7

2,82,9

2,72,7

2,8

3,23,1

80 MA880 MB8

90 S890 L8

100 LA8100 LB8

112 M8

132 SA8132 MA8

0,180,25

0,370,55

0,751,1

680690

675680

680695

700

710710

49,353,8

55,960,9

67,670,2

75,8

80,781,0

0,650,68

0,660,69

0,660,66

0,71

0,700,70

0,81,0

1,41,9

2,43,4

4,0

5,67,6

2,53,5

5,27,7

10,515,1

20,5

29,640,3

Ex d IIC, Ex de IIC

D6•D6•

D6•D6•

D6•D6•

D6•

D6•D6•



MOMENTOF INERTIA

WEIGHTIM 1001

RATEDOUTPUT

MOTOR TYPE

J

[kgm2]


TMAX / Tn

p.u.p.u. p.u.

Ts / Tn

SPEED EFFICIENCY

RATEDCURRENT

I

[A]

RATEDTORQUE

Tn

POWERFACTOR

COS


STARTINGCURRENT

STARTINGTORQUE

Is / In

400V 50Hz


[kW] [rpm]

[Nm]

[kg][%]

8 poles = 750 rpm


D6•

D5•



50 Hz

160 MA8160 MB8160 L8

D5•D5•D5•

180 L8D5•

200 L8D5•

225 S8225 M8

D5•D5•

250 M8D5•

280 S8280 M8

D5•D5•

315 SM8315 MA8315 MC8315 MD8315 ME8

D5•D5•D5•D5•D5•

1,5

2,23

45,57,5

11

15

18,522

30

3745

557590

110132

710720720

725

725

730730

730

735735

740740740740740

81,082,484,7

86,7

88,0

89,090,0

91,0

92,593,0

93,593,894,494,594,6

0,730,740,74

0,75

0,75

0,760,76

0,76

0,800,80

0,820,820,830,830,83

9,813,017,3

24,4

32,8

39,546,4

63,0

72,087,0

104139166202243

547399

145

197

242288

392

480569

709967116014181702

4,24,24,2

4,5

5,0

5,25,3

5,5

6,06,0

6,56,06,26,26,2

1,91,92,0

2,0

2,1

2,22,2

2,3

2,52,5

2,32,12,22,22,2

2,12,12,1

2,2

2,3

2,42,4

2,5

2,52,5

2,42,22,32,32,3

0,0800,0920,110

0,160

0,220

0,4200,520

0,620

1,0501,250

2,802,803,504,004,30

140151184

255

280

324340

405

505640

10501050128013701440

ASI.CT.035.4 GB

14

30

5

16

M5

12,5

19

40

6

21,5

M6

19

24

50

8

27

M8

19

28

60

8

31

M10

22

38

80

10

41

M12

28

42

k6

110

12

45

48

110

14

51,5

55

110

16

59

60

140

18

64

65

140

18

69

70

m6

140

20

74,5

M20

42

75

140

20

79,5

80

170

22

85

90

170

25

95

M16

36

Dtoll.E

F h9GADBEG

j6

SHAFT EXTENSIONTapped holes as

per DIN 332

GA EEG

D

DB

F

ASI.CT.035.4 GB

TERMINAL BOX AND CABLE ENTRYThe terminal box is located on top of the motor (referred to a B3 mounting) for all sizes from 71 to 315, usually equipped with 6 terminals, and it can be rotated

by steps of 90° (from size 90). For 71 ÷ 80 frame size the cable entry is on the right side of the motor (seem from the D side).

M6

M6

M6

M8

M12

Frame Size (mm) Threaded terminals

71 - 80

90 - 132

160 - 200

225 - 250

280 - 315

Cable entries for Main Connection

M25 X 1,5

M32 X 1,5

2 x M40 x 1,5

2 x M50 x 1,5

2 x M75 x 1,5

Cable entries for Auxiliary Connection

-

-

-

M20 X 1,5

M20 X 1,5

DRAINAGE HOLE A drainage hole is available on request from frame size 132 (only for horizontal mounting).

THERMAL PROTECTION Motors with a frame size 90 mm are provided with 3 PTC in their standard configuration. PTC, PT100 and Space Heaters areavailable on request according to the following table:

(*) PT100 optional from frame size 132.

OPTIONS Other options are available on request. Please contact Marelli Motori for more information and/or quotation.

FREQUENCY COVERTER SUPPLY

Please contact Marelli Motori for specific data sheet and quotation relevant to Ex d/de IIC motors fed by frequency converter.

Frame size

71 - 80

90 - 132

160 - 180

200 - 225

250 - 315

Type ofprotection

d

de

d

de

d

de

d

de

d

de

optional

standard

standard

standard

standard

PTC PT 100

-

optional

optional

optional

optional

AnticondensationHeaters

-

optional

optional

optional

optional

PTC + Heaters PT100 + Heaters

-

optional*

optional

optional

optional

-

-

optional

optional

optional

BEARINGSThe regreasind system is standard for frame sizes 280 and 315 and available on request for frame sizes 180 to 250. Bearings without screen only will be used

whenever the regreasing nipples are mounted.

6202-2Z

6204-2Z

6205-2Z

6206-2Z

6206-2Z

6308-2Z

Frame Size(mm)

D - end N - end

71

80

90

100

112

132

160

180

200

225

250

280

315

4 poles

6202-2Z

6204-2Z

6205-2Z

6206-2Z

6206-2Z

6308-2Z

6209-2Z-C3

6209-2Z-C3

6210-2Z-C3

6213-2Z-C3

6213-2Z-C3

6314-Z-C3

6316-C3

NU210-EC-C3

NU210-EC-C3

NU212-EC-C3

NU213-EC-C3

NU214-EC-C3

6314-2-C3

6316-C3

NU210-EC-C3

NU210-EC-C3

NU212-EC-C3

NU213-EC-C3

NU214-EC-C3

NU2217-EC-C3

NU2219-EC-C3

2 poles

SURFACE PROTECTIONThe following table shows the available external protection. Different colours RAL or MUNSELL are available on request.

Sanding and/or degreasing

Epoxy-Vinyl

-

Polyurethane

> 50

RAL5010

Standard

Surface

Undercoating

Coat

Finishing

Total thickness (µm)

Colour

Sanding and/or degreasing

Epoxy-Vinyl

Polyurethane

Polyacrilic

180

RAL5010

Special

U S AFKI Marelli-USA

1524 Lebanon Road

Danville, KY 40422 - USA

(P) +1.859.236.6600

(F) +1.859.236.8877

e-mail: [email protected]

C E N T R A L E U R O P EMarelli Central Europe GmbH

Heilswannenweg 50

31008 Elze - Germany

(P) +49.5068.462-400

(F) +49.5068.462-409


S O U T H A F R I C AMarelli Electrical Machines South Africa (Pty) Ltd

Unit 4

55 Activia Rd-Activia Park

Elandsfontein, 1406

Gauteng

Republic of South Africa

(P) +27.11.8225566

(F) +27.11.8288089


G R E A T B R I T A I NMarelli UK Ltd

Meadow Lane

Loughborough

Leicester

LE 11 1NB - UK

(P) +44 1509.615518

(F) +44 1509.615514


A S I A P A C I F I CMarelli Asia Pacific Sdn Bhd

Lot 7, Jalan Majistret U1/26

Hicom - Glenmarie Industrial Park

40150 Shah Alam

Selangor D.E., Malaysia

(P) +60.3.7805.3736

(F) +60.3.7803.9625


M A R E L L I M O T O R I O V E R S E A S O F F I C E S :

ASI.CT.035.4 GB MARELLI MOTORI reserves the right to change the design, technical specification and dimensions in order to update or improve its products, without prior notice.

MarelliMotori S.p.A.

®

HEADQUARTERS

Marelli Motori S.p.A.

Via Sabbionara, 1

36071 Arzignano (VI) Italy

(T) +39.0444.479711

(F) +39.0444.479888

web: www.marellimotori.com


ITALIAN OFFICES

Milan

Via Cesare Cantù, 29

20092 Cinisello Balsamo (MI) Italy

(T) +39.02.660.131.66

(F) +39.02.660.134.83


Florence

Via Panciatichi, 37/2

50127 Firenze - Italy

(T) +39.055.431.838

(F) +39.055.433.351


Gra

fiche M

arc

oli

n S

chio

20

98

Documents

A55-76-it