ABB Switchgear Limited
P.O. Box 83-203
Edmonton, Henderson, Auckland 8, New Zealand
Tel: 0064 9 837 1234
Fax: 0064 9 837 2950
September 2001
Revision: A
SYSTEM FOR
VOLTAGE INDICATION AND PHASE BALANCE TEST
FOR SAFELINK & SD SWITCHGEARS
TABLE OF CONTENTS
PAGE
1. VOLTAGE INDICATION
3
1.1 Introduction
1.2 System description
1.3 Technical data
1.4 Operation
3
3
3
3
2. PHASE BALANCE TEST
3
2.1 Introduction
2.2 System description
2.3 Technical data
2.4 Operation
3
4
4
4
3. TEST OF VOLTAGE INDICATOR & SELF-TEST
3.1 Test of voltage indicator
3.2 Testing the phase balance tester (self-test)
4. PICTURES
5
5
5
5
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1. VOLTAGE INDICATION
1.1 INTRODUCTION
There is always some operational risk when earthing switchgear. To minimise this risk, earthing is
performed with a mechanically interlocked earth switch with full fault making capacity. In addition to
this, switchgear can include a system for voltage indication on each phase of the cable bushing.
1.2 SYSTEM DESCRIPTION
The voltage indicating system consists of:
*
Three cable bushings, with built-in capacitive screens (one per phase) for voltage indication.
*
One cable stem consisting of three shielded cables (one per phase), for transmission of the
measured voltage from the insulators to the front panel.
*
One front panel with sockets for the voltage indicator.
*
One voltage indicator with display to indicate voltage on the three phases.
1.3 TECHNICAL DATA
The maximum short-circuit current from front panel at rated voltage 12kV is 45µA.
The maximum open circuit voltage at rated voltage 12kV is <=50V.
The screen capacitance is very low, approx. 23pF.
Cable capacitance is approx. 60pF at rated voltage 12kV.
1.4 OPERATION
Plug in the voltage indicator in the front panel.
If the display show 1, 2 or 3 the related phases are live (the voltage to neutral is >=350V at rated
voltage 12kV.
2. PHASE BALANCE TEST
2.1 INTRODUCTION
Before closing a new incoming feeder in live switchgear it can be important to check that the cables
are connected to the right phases by testing the phase balance between the two systems. Therefore
SafeLink/SD offers a system for phase balance test.
With the phase balance tester you can also check the function of the voltage indicator (see chapter
3).
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There is also a possibility to test the phase balance tester itself (see chapter 3).
Notice that this system should not be used for synchronization.
2.2 SYSTEM DESCRIPTION
The phase balance tester is an electronic unit, for phase balance test between a known and an
unknown phase, that uses the same system as the voltage indicator i.e. the cable bushings (with the
built-in capacitive screen), the cable stem and the front panel.
Article nr.
Description
5697 889-B
Phase balance tester
Rated voltage
kV
3.6 - 12
2.3 TECNICAL DATA
The phase balance tester can be used with the front panel, 12 kV.
Phase position is indicated at operating voltage >= 3 kV in the cubicle.
Phase balance is indicated if the phase displacement is less than 40 degrees.
Unloaded output voltage from output side marked TEST OF VOLTAGE IND. is a square wave
with peak-peak voltage 9 V. Loaded output voltage is a square wave with peak-peak voltage 0.6
V.
2.4 OPERATION
Switch on the battery-switch marked with a battery symbol. If the battery is OK the green LED
marked BAT should blink.
On the right side of the phase balance tester there are two inputs (signal ~ and earth 0) marked A
and two inputs (signal ~ and earth 0) marked B.
Plug in on A one phase and earth from one front panel e.g. L1 and 0 from the front panel for the
busbar, and on B the related phase and earth from another front panel e.g. L1 and 0 from the front
panel on the incoming cubicle. Use cables with 4 mm banana pin.
Two yellow LEDs marked UA and UB indicates (blinks) if there is enough measuring voltage into
the phase balance tester (corresponds to >= 3 kV operating voltage in the switchgear cubicle). If
those two LEDs are blinking, the phase balance test is made. The result is indicated by a green or a
red LED.
If the green LED marked UA=UB is blinking, there is phase balance between the two incoming
cables.
If the red LED marked UA#UB is blinking, there is not phase balance between the two incoming
cables.
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WARNING: On the input side (right side) marked A and B on the phase balance tester, you may
only plug in cables from the front panels or from the output side (left side) of the phase balance tester
marked TEST OF VOLTAGE IND. Otherwise there is a risk that the tester will be damaged.
3. TEST OF VOLTAGE INDICATOR & SELF-TEST
3.1 TEST OF VOLTAGE INDICATOR
On the output side (left side) of the phase balance tester there are outputs marked TEST OF
VOLTAGE IND. for test of the voltage indicator.
Plug in the voltage indicator and switch on the battery-switch.
If the voltage indicator is OK you should see 123 on the display. If there is nothing on the display or
if one digit is missing the voltage indicator is probably defect.
3.2 TESTING THE PHASE BALANCE TESTER (SELF-TEST)
To test the phase balance tester use cables (4 mm banana pin) to connect the output side marked
TEST OF VOLTAGE IND. with the input side marked A and B. See picture 1.
To test the indication of phase balance do as follows:
- Connect a cable between one of the outputs marked 0° and the signal ~ input marked A.
- Connect a cable between the other output marked 0° and the signal ~ input marked B.
- Switch on the battery switch.
If everything is OK the LEDs marked UA, UB and UA=UB (phase balance) should blink.
To test the indication of phase opposition you do as for phase balance test (above), except that you
move one of the plugs on the output side marked 0° to the output marked 180°.
If everything is OK the LEDs marked UA, UB and UA#UB (phase opposition) should blink.
5. PICTURES
Picture 1
Picture 2
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Picture 3
Picture 4
Picture 5
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