CP TC12Reference Manual

OIL TEST CELL

2

CP TC12

Manual Version: CPTC12.AE.2

© OMICRON electronics 2006. All rights reserved.

This Reference Manual is a publication of OMICRON electronics GmbH.

All rights including translation reserved. Reproduction of any kind, e.g., photocopying, microfilming orstorage in electronic data processing systems, requires the explicit consent of OMICRON electronics.Reprinting, wholly or in part, is not permitted.

This Reference Manual represents the technical status at the time of printing. The product information,specifications, and all technical data contained within this reference manual are not contractuallybinding. OMICRON electronics reserves the right to make changes at any time to the technology and/orconfiguration without announcement. OMICRON electronics is not to be held liable for statements anddeclarations given in this reference manual. The user is responsible for every application described inthis reference manual and its results. OMICRON electronics explicitly exonerates itself from all liabilityfor mistakes in this manual.

OMICRON electronics translates this manual from its source language English into a number of otherlanguages. Any translation of this manual is done for local requirements, and in the event of a disputebetween the English and any non-English versions, the English version of this manual shall govern.

Table of Contents

Table of Contents

Safety Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

2 Measuring Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

3 Connecting CP TC12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

4 Components of CP TC12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

5 Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

6 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Contact Information / Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . .15

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

3

OMICRON Test Universe

4

Safety Instructions

Safety InstructionsImportant: High voltage tests are only permitted to operators that are particularly skilled and experienced in high voltage testing!

During the entire test the operator is responsible for complying with all applicable safety requirements.

The metallic container of CP TC12 represents the high voltage electrode. During the test, this part carries a voltage of up to 12 kV. Therefore, treat the area around CP TC12 as "prohibition zone" according to EN 50191. Make sure that nobody can enter this zone

during the test. Use walls or barriers for protection like it is shown in figure on page 12.

Since a possible capacitive coupling can create a very high touch voltage, do not place the container onto a metallic or conducting surface.

Before carrying out tests with high voltage, please carefully read the following safety instructions:

• Do not perform any test without having read this CP TC12 manual as well as the CPC 100 and the CP TD1 manuals!

• In particular, carefully read all safety instructions and follow them!

• Do not use the test equipment without a steady connection to substation ground!

• Comply with all applicable national and international standards for a safe operation of high voltage test equipment (EN 50191, IEEE 510 and others).

• Never touch any terminal without a visible earth connection!

FOR YOUR OWN SAFETY

Always follow the 5 safety rules:

1.Insulate

2.Secure to prevent reconnecting

3.Check isolation

4.Earth and short-circuit

5.Cover or shield neighbouring live parts

5

CP TC12

1 IntroductionCapacitance (C) and Dissipation Factor (DF) measurement is an established and important insulation diagnosis method. It can detect:

• Aging of insulation liquids

• Contamination of insulation liquids with particles

• Water in liquid insulation

In an ideal capacitor without any dielectric losses the insulation current is exactly 90° leading according to the applied voltage. For a real insulation with dielectric losses this angle is less than 90°. The angle δ = 90° - ϕ is called loss angle. In a simplified diagram of the insulation, Cp represents the loss-free capacitance and Rp the losses (see figure 1-1).

Figure 1-1:Simplified circuit diagram of a capacitor

The definition of the dissipation factor and the vector diagram are shown in figure 1-2.

ICP

U CP

IRP

RP

I

6

Introduction

Figure 1-2:Definition of dissipation factor (tan δ) and the vector diagram

The correlation between the Dissipation Factor and Power Factor (PF = cos ϕ) and the vector diagram are shown in figure 1-3.

Figure 1-3:Correlation between DF and PF

Re

IRp

U

ICp

I

j Im

δ

δtanIRpICP----------- 1

1 ωCp×--------------------

with ω 2 π f××

and f frequency=

=

==

Im

ICN ICX

δ

ϕ

UORe

Withδ 1

δ δ ϕ

δ

sin≅tan≅

«

π2--- ϕ–=

PF DF1 DF2+------------------------=

DF PF1 PF2–-----------------------=

7

CP TC12

Figure 1-4 shows the breakdown voltage and the DF in oil, dependent on the water content. With low water content, the breakdown voltage is very sensitive; with higher water content, the DF is a good indicator.

Figure 1-4:Breakdown voltage and DF in oil, dependent on the water content

Figure 1-5 shows the DF of new and used oil, dependent on the temperature. With higher temperatures, the viscosity of the oil decreases so the particles, ions and electrons can move easier and faster. Thus the DF increases with temperature.

Figure 1-5:DF of new and aged oil, dependent on temperature

1 = new oil2, 3 and 4 = used oil

kV/cm

600

500

400

300

200

100

0

60

50

40

30

20

10

0

Bre

akdo

wn

volta

ge

Dis

sipa

tion

fact

or

0 20 40 60 80 100 120 140 160 180 200Water content mg/kg

tan δ

εd

0/00

0/00

tan

δ

104

103

102

101

1-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 °C

Oil temperature

1

2

3

4

8

Introduction

For mineral oil the dissipation factor is generally measured at 90° C according to IEC.

When the dissipation factor is measured at 20° C, the values are about to of the 90°C values.

110------ 1

20------

9

CP TC12

2 Measuring PrincipleIn the measuring schematic figure 2-1, the guard (ring) is shown as cut surface.

Figure 2-1:Measuring schematic

Figure 2-2:Measurement settings

Note: Whereas the 12 kV measuring voltage in figure 2-2 are just an example, we recommend to use the averaging factor (number of measurements) setting of Ø = 10 at any rate.

UST-A

GuardPlexiglass

10

Measuring Principle

Figure 2-3 shows the oil test cell’s minimum oil level, which should be slightly above the lower egde of the guard.

Figure 2-3:Minimum oil level

Plexiglass

Guardminimum oil level

11

CP TC12

3 Connecting CP TC12Figure 3-1 shows a typical test setup with CP TC12 connected to CP TD1. Keep a minimum of 50 cm (20 inches) from the test cell to the barriers in all directions, and make sure that high voltage warning signs are well visible!

Figure 3-1:Typical test setup

Figure 3-2:Oil test cell CP TC12

*) Rather than using the blue CP TD1 cable, the guard can alternatively be connected to the green connector of the high voltage cable. In UST-A mode, either method you choose, technically there is no difference.

The container housing carries very high voltage. To avoid electrical spark-over between the two CP TD1 connecting cables and the housing, keep the cables at least 10 cm (4 inches) away from the housing.

> 50 cm

blue (guard)red (meas. electrode)

Connectingcables toCP TD1

Guard

Plexiglass cover

Highvoltage

cableAlternative guard connector *)

> 10 cm

12

Components of CP TC12

4 Components of CP TC12Figure 4-1 shows the disassembled oil test cell.

Figure 4-1:Disassembled oil test cell CP TC12

High voltage electrode(container)

Connector for high voltage cable

Measuring electrode

Plexiglass coverBase

Guard

Washer

Retainer

13

CP TC12

5 Technical DataThree electrode design with guard for precise measurement especially of small losses, electrodes out of stainless steel.

• Test gap: 11 mm

• Capacitance of empty cell (air): approx. 65 pF ± 10 %

• Sample volume: 1.2 l (min) to 2 l (max)

• Max. RMS test voltage: 12 kV

• Dimensions: 220 mm x 250 mm(87" x 102")[diameter x height]

• Weight: appr. 9 kg

• Dimensions of case: 390 mm x 390 mm x 400 mm (153.5" x 153.5" x 157.5")[ length x width x height]

• Weight with case: approx. 12 kg

6 CleaningClean the cell with warm water and a dishwashing detergent. The plexiglass cover may not be exposed to temperatures higher than 60°C. Do not use Alcohol for cleaning the Plexiglas cover.

14

15

Contact Information / Technical Support

Contact Information / Technical Support

Europe, Africa, Middle EastOMICRON electronics GmbH

Phone: +43 5523 507-333

E-Mail: support@omicron.at

Web: www.omicron.at

Asia, PacificOMICRON electronics Asia Ltd, Hong Kong

Phone: +852 2634 0377

E-Mail: support@asia.omicron.at

Web: www.omicron.at

North and South AmericaOMICRON electronics Corp. USA

Phone: +1 713 830-4660 or 1 800 OMICRON

E-Mail: techsupport@omicronusa.com

Web: www.omicronusa.com

For addresses of OMICRON offices with customer service centers, regional sales offices or offices for training, consulting and commissioning please see our website.

OMICRON Test Universe

16

Index

Index

Aaveraging factor (number of measurements) 10

Bbreakdown voltage and DF in oil . . . . . . . . . . . 8

Ccapacitance measurement . . . . . . . . . . . . . . . 6case for CP TC12 . . . . . . . . . . . . . . . . . . . . . 14cos Phi

correlation to dissipation factor . . . . . . . . . 7

Ddielectric losses . . . . . . . . . . . . . . . . . . . . . . . . 6dissipation factor

correlation to power factor . . . . . . . . . . . . . 7definition . . . . . . . . . . . . . . . . . . . . . . . . . . 7depending on temperature . . . . . . . . . . . . . 8for mineral oil . . . . . . . . . . . . . . . . . . . . . . . 9of new and used oil . . . . . . . . . . . . . . . . . . 8

dissipation factor measurement . . . . . . . . . . . 6

Ggrounding CP TC12 . . . . . . . . . . . . . . . . . . . . 5

Hhigh voltage electrode . . . . . . . . . . . . . . . . . . 5

Iinsulation diagnosis . . . . . . . . . . . . . . . . . . . . 6

Llevel

oil level in test cell . . . . . . . . . . . . . . . . . . 11

Mmeasuring

capacitance . . . . . . . . . . . . . . . . . . . . . . . . 6dissipation factor . . . . . . . . . . . . . . . . . . . . 6

mineral oildissipation factor of . . . . . . . . . . . . . . . . . . 9

Ooil level in test cell . . . . . . . . . . . . . . . . . . . . 11

Ppower factor

correlation to dissipation factor . . . . . . . . . 7prohibition zone acc. to EN 50191 . . . . . . . . . 5

17

OMICRON Test Universe

Ssafety instructions . . . . . . . . . . . . . . . . . . . . . . 5spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . 13

UUST-A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

18