Development and evaluation of nitrile rubbers seals for power transformer application

Avila, Mauro Cesar de; Munaro, Ana Paula; Munaro, Marilda

doi:10.1590/0104-1428.20210040

Brazil

home Table of contents navigate_before previous current next navigate_next

home Table of contents

ORIGINAL ARTICLE • Polímeros 32 (2) • 2022 • https://doi.org/10.1590/0104-1428.20210040 linkcopy

Development and evaluation of nitrile rubbers seals for power transformer application

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Mineral insulating oil (MIO) and natural ester insulating (NEI) oil are used in power transformers as an insulating fluid, while elastomeric seals are usually composed of nitrile rubber (NBR). The proprieties of these seals can change in contact with insulating oil. Variation in sealant properties is undesirable in power transformers. In this work, the variation of some elastomer properties was evaluated before and after accelerated aging in MIO and NEI. The developed elastomeric compositions showed variation in the stress and strain at break after the aging test. It also appeared that MIO penetrated the samples and that dioctylphthalate (DOP) migrated or was extracted into MIO and NEI. The samples vulcanized with peroxide showed better results than those vulcanized with sulfur.

Keywords:
compatibility; mineral insulating oil; natural ester insulating; nitrile rubber; power transformers

	TYPICAL VALUE
Neutralization Index	0.01 mg KOH/g oil
Water	20 ppm
Density at 20 °C	0.887 g/cm³
Power factor at 90 °C	0.04%
Flash point	150 °C
Viscosity at 40 °C	9.32 cSt
Viscosity at 100 °C	2.31 cSt
Pour point	-60 °C

	TYPICAL VALUE
Neutralization Index	0.02 mg KOH/g oil
Water	54 ppm
Density at 20 °C	0.9192 g/cm³
Dielectric losses at 20 °C	0.13%
Dielectric losses at 100 °C	3.9%
Flash point	308 °C
Viscosity at 40 °C	35.99 cSt
Viscosity at 100 °C	8.57 cSt
Pour point	-7 °C
Flash point	342 °C

	A	B	C	D
NBR 35LM	100.0	100.0	100.0	100.0
Polymeric Plasticizer	20.0	-	20.0	-
DOP	-	20.0	-	20.0
N 339	30.0	30.0	30.0	30.0
N 762	40.0	40.0	40.0	40.0
Zinc oxide	4.0	4.0	4.0	4.0
Stearic acid	1.0	1.0	1.0	1.0
Resin A-80	8.0	8.0	8.0	8.0
Antioxidant	1.0	1.0	1.0	1.0
Antiozonant	1.0	1.0	1.0	1.0
Sulfur	1.6	1.6
MBTS	1.5	1.5
TMTD	0.2	0.2
Peroxide 40%	-	-	4.0	4.0

	HARDNESS (Shore A)	STRESS AT BREAK (MPa)	ELONGATION (%)
Sample A	55 ± 1	19.8 ± 0.60	1430 ± 5
Sample B	57 ± 1	22.4 ± 0.67	1230 ± 6
Sample C	48 ± 1	18.8 ± 0.56	1450 ± 6
Sample D	48 ± 1	16.8 ± 0.50	1210 ± 3

	SAMPLES
	A	A MIO	A NEI	B	B MIO	B NEI	C	C MIO	C NEI	D	D MIO	D ENI
Loss mass (%)	4.18	9.33	1.2	12.30	9.60	1.60	1.22	9.26	1.3	9.00	9.00	0.50

vertical_align_top file_download show_chart

more_horiz close
- image
- translate
- link
- article
- vertical_align_top
- file_download
- show_chart
- image
- translate
- link
- article

location_on

Associação Brasileira de Polímeros Rua São Paulo, 994, Caixa postal 490, São Carlos-SP, Tel./Fax: +55 16 3374-3949 - São Carlos - SP - Brazil
E-mail: revista@abpol.org.br

rss_feed Stay informed of issues for this journal through your RSS reader

Accessibility / Report Error