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NH 91u, NH 91 LVu, NH 91 MVu

Application

They are designated for impregnation of mechanically and thermally stressed windings of electrical rotating machines and transformers of thermal class H by discontinue dipping or flooding technology under atmospheric pressure or under vacuum and pressure.

Characteristics

NH 91u, NH 91 LVu, NH 91 MVu are one-component impregnating resins based on solution of modified unsaturated polyester resin in dialyphtalate. They are cured for 2h by 130°C since reaching corresponding temperature in winding. Impregnating resins are resistant to refrigerator liquids, transformer oils and radioactive radiation.

Tab.1 Processing data

NH 91u NH 91 LVu NH 91 MVu
Density (DIN 53 217) 25 °C [kg/m3] 1130 - 1180 1130 - 1140 1150 - 1180

Flow time

(DIN Cup 4)

25 °C

40 °C

 [s]

110 - 150

40 - 50

50 - 80

180 - 280
Viscosity 25 °C [mPa.s] 550 - 750 240 - 400 900 - 1400
Shelf-life max. 25°C [month] min. 12 min. 12 min. 12

Flash point (Cleveland)

 [°C] 145 145 145
Saturated vapors pressure

25 °C

100 °C

 [mbar]

0,0013

0,26

0,0013

0,26

0,0013

0,26
Gel time 1) 130 °C [min] 10 - 17 10 - 17 10 - 17

Pot life
(criterion: increasing of viscosity to double)

 50 °C [dní] 50 50 50

Test of effect of impregnating resin on enameled wires 2), 8)

Decrease of hardness according to pencil

 0 - 1 0 - 1 0 - 1

Tab.2 Properties after cure

NH 91u NH 91 LVu NH 91 MVu
Drying to depth 3), 4) I. 1.1.1.9)
0. 1.1.1.		 I. 1.1.1.9)
0. 1.1.1.		 S 1
U 1
I. 1.1.
Curing of test specimen 150°C [h] 4 4 4
Electric strength 5) 23 °C [kV/mm] 120 - 150 120 - 150 120 - 150
Volume resistivity4)
23°C
155°C
180 °C
after 96h in water		 [Ω.m]

1014
1011
1010
1013

1014
1011
1010
1013

1014

1010
1013
Twisted coil test 6)
23 °C
155 °C
180 °C		 [N]

350 - 400
120 - 150
80 - 100

 300 - 350
130 - 160
90 - 120

300 -350

80 - 100
Helical coil test 6)
23 °C
155 °C
180 °C		 [N] 200 - 250
100 - 120
60 - 90		 200 - 250
100 - 120
60 - 90

180 - 200

40 - 60
Glass transition temperature (Tg) [°C] 140 140
Thermal endurance 7) Test criterion:
Bond strength 22 N (Helical coil)		 [°C] 183 183 183
Thermal endurance 7) Test criterion:
Breakdown voltage 700 V (Twisted pairs)		 [°C] 181 181 181

1). DIN 16 945  Method A                                   
2). STN 67 3150 čl. 11, met. B after 60 min at 70 °C
3). 4,5h by 100°C + 1,5h by 110°C + 2h by 120°C
4). DIN 46 448 Blatt 1
5). NEMA Standard RE 2 – 1987
6). STN IEC 61033
7). STN IEC 60216
8). Polyesterimid; Polyesterimid + amidimid
9). Specimen appearance: hard, free of leaks and bubbles, surface smooth, non tacky

Impregnating resins complied with tests done in German state laboratory.
Test protocol: PTB Nr. III B/C-706 U

Impregnating resins complied with tests done in American laboratory Underwriters Laboratories Inc.
Test protocol: UL E233982

Packing and storage

Impregnating resin is delivered in non-returnable, clean, for other products not used drums DG 55 with capacity 216,5l, eventually in packages according to agreement between producer and client.
 
Impregnating resins are stored in tightly closed packages in dry ventilated warehouse by max.+25°C, which complies with STN 65 0201.