ABB VT Guard Pro Parts list manual

VT Guard Pro / VT Guard Pro-D
Solution for ferroresonance elimination

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Scope of Contents:
1. Description 2
2. Application and settings 2
3. Installation 5
4. Operating condition 7
5. Technical parameters 7
6. Dimensional drawing 8
7. Maintenance and service 8
8. Warranty 8
9. Disposal 9

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1. Description
VT Guard Pro is an advanced security device which protects MV inductive voltage transformers (VTs) against
ferroresonant oscillations. It is designed to be used in open-delta connection of three single-phase VTs.
Ferroresonant oscillations may be initiated by transient events (such as switching operations) in power networks. The
undamped ferroresonant oscillations are dangerous to the equipment installed due to large overcurrents and
overvoltages which may lead to permanent damage of the equipment. VT Guard Pro belongs to a new family of
advanced protection devices which protect VTs against ferroresonant phenomena by proper and prompt damping
action (Fig. 1), without creating excessive power consumption (as in case of using ordinary damping resistors) during
normal operation of the network.
Two versions of the VT Guard Pro are available:
a) VT Guard Pro
b) VT Guard Pro–D
Both versions are identical from functionality point of view (dumping ability), but the VT Guard Pro–D has extended
functions which allows self-diagnostic. This diagnostic feature allows the device to check itself (functionality of its
circuits) and is able to send information about its state into a superior system.
Fig. 1 – Demonstration of VT Guard Pro effectiveness – dumping action

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2. Application and settings
a) VT Guard Pro
VT Guard Pro should be connected in open delta configuration of three single-phase VTs, as shown in Fig. 22.
Nominal voltage level of the winding used for open-delta configuration should be 100/3 V or 110/3 V and it should
be design at least for nominal current 4A.
Manufacturer does not guarantee proper operation and performance of
VT Guard Pro in case of its use in different applications or at different
voltage levels. In such case contact manufacturer for further details.
In case some other device for ferroresonance elimination is already
installed in the open-delta winding of VT, it has to be removed from this
circuit before VT Guard Pro installation.
Live end of the open delta configuration (da1 - terminal on Fig. 22) should be connected into X1:1 terminal, earthed
end (dn3 - terminal on Fig. 22 to the X1:2 terminal. In case, the earth-fault protection device is already connected in
open delta configuration, the VT Guard Pro should be connected in parallel to such protection device.
Fig. 2 – Connection diagram of VT Guard Pro
Factory default setting for the threshold voltage of VT Guard Pro (effective voltage level when the device is activated)
is 20 V and time delay (time between reach of threshold voltage and dumping action – introduced in order to keep
functions of external protection device unaffected) is 1,4s. These settings cover the majority of the applications, but
can be changed if necessary. In that case, the device has to be disconnected from the power (both functional and
diagnostic part) at least for 20s before setting change. The setting change is done by jumpers, after opening the
cover– one jumper is for threshold voltage selection, the other for time delay Fig..
Possible adjustment:
Threshold voltage ……………..20, 25, 30 V
Time delay …………………….0,4; 1,4; 2,4; 3,4s
b) VT Guard Pro-D
The internal settings (threshold voltage, time delay) and connection of the functional part (Terminals X1:2, X1:2)
Fig.
3– Jumper setting

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should be done the same way as in the case of VT Guard Pro (Fig. 22, Fig.) Separate power supply is needed for
diagnostic part. There are two recommended ways how to supply power to the diagnostic part (described in Fig. 4
and Fig. 55).
The earthed star-point (n1, n2, n3) has to be connected to the X2:1 terminal (diagnostic part)
and earthed part of the open delta (dn3) configuration to the terminal X1:2 (functional part), for the connection
on Fig. 4.
Fig. 4– Recommend connection of the diagnostic supply
Fig. 5 – Recommend connection of the diagnostic supply

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The VT Guard-D has self-check functions. The status of the device is indicated by
Diodes, which are placed in such a way, that they are visible (only when activated) through unused holes at the
screw terminal holes on the right side, position 17 - RED, 18 –GREEN
Fig. 6.
LED indication
Description
RED
GREEN
- Diagnostic power is OFF
X - Diagnostic power is ON
- Device OK
X - Diagnostic power is too low
- Circuit error occured
X X - Diagnostic power is too low or
circuit error occured
a) OK b) internal failure
Fig. 6– Device status, LED position
Terminals X3:1 and X3:2 (see Fig. 4, Fig. 55). In case of proper operation, auxiliary contacts are switched on.
Superior system (e.g. protection relay - separate device with available binary inputs/outputs) sends and receives
the same signal through these terminals. In case of internal failure, there is no signal flowing through.
3. Installation
VT Guard Pro should be fitted in low-voltage compartment of the MV switchgear at the DIN – TS 35 rail
Fig. 77 in vertical position at least 20 cm from other thermal sources. Connection should be done according to the
Fig. 4 or Fig. 55 by insulated wires (minimum cross-section should be 1,5 mm2, maximum –2,5 mm2). Max.
length of the connection wires up to 150 m.
Minimum temperature wires rating is 75°C!
The device should be
connected via switches /isolators (–FD1, -FD2) according to (Fig. 22, Fig. 4, Fig. 55) to meet IEC 61010-1 (CE
marking). If the switches/isolators are not used it has no impact on the device functionality. The device contains self-
protection components which disconnect device in case of internal failure.
functional (terminals X1:1, X1:2)….-FD1,resistive load AC1, min 15A tripping ability, recommended device -
ABB isolator E202
diagnostic (terminals X2:1, X2:2, X2:3)…-FD2, resistive load AC1, min 1A tripping ability, recommended device -
ABB isolator E203
The switches shall be in close proximity to the device and within
easy reach or an operator.
The switches shall be marked as the disconnecting device for the
equipment.

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Fig. 7 – DIN – TS 35 fixing
Device part
Functional
X1:1
open delta configuration - live end
0 - 110 V AC
X1:2
open delta configuration - earthed end
earthed
Diagnostic
X2:1
measurement/residual winding - earthed
earthed
X2:2
measurement/residual winding - live end
33 - 110 V AC
X2:3
measurement/residual winding - live end
33 - 110 V AC
Auxiliary
contacts
X3:1
closed in normal condition
230 V AC
220 V DC
X3:2
Tab. 1 – Terminals position
All of assembly work should be done after transformers
disconnection from network.
It is forbidden to open VT Guard enclosure under voltage or with
connected leads from the voltage transformers
It is forbidden to do any manipulation or changes inside of the
device, except of jumper setting (Fig.). Jumper setting to be done
by authorized and trained personnel only.
If the device is used in a manner not specified by the
manufacturer, the protection provided by the equipment may be
impaired

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4. Operating condition
Appliance should be working indoor, with ambient temperature from -25 °C to +50 °C and humidity up to 90 %, not
condensing water.
No one should touch terminals with metallic objects, when
appliance is under voltage.
It is forbidden to place any objects close to or into ventilation
gaps of the device.
In case of improper work or failure, it is necessary to
separate appliance from system and replace with a new
device.
5. Technical parameters
Device part
Functional
Rated operational voltage Ue 100 / 110
V AC
Max. operational current Iemax 10 A/0,2s
Voltage range U 0-110
V AC
Nominal frequency fn 50/60
Hz
Time delay td 0.4, 1.4, 2.4, 3.4
s
Threshold voltage Ut 20, 25 ,30
V
Selfconsumption P <0.1
W
Diagnostic
Rated control supply voltage US 100/V3, 100/3
V AC
Voltage range U 33-110
V AC
Nominal frequency fn 50/60
Hz
Selfconsuption PD< 2
W
Auxiliary
contacts Rated control circuit voltage UC 230 (max. 100mA)
V AC
220 (max. 100mA)
V DC
Operating ambient temperature
-
-25°C ... +50
°C
Storage & transportation temperature
-
-40°C ... +85
°C
Humidity - up to 90
%
Protection class
-
IP 20

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6. Dimensional drawing
7. Maintenance and service
It is important to keep VT Guard Pro in cleanliness. Special attention should be paid to cleanliness of air-ventilation
gaps. In case, of choked air-ventilation gaps the device should be disconnected from the circuit (both functional and
diagnostic part), then the air-ventilation gaps can be cleaned by brush or compressed air. Other preventive
maintenance is not needed.
Any repairs must be done only by authorized personnel.
Manufacturer does not take responsibility for improper
device functioning in case of unauthorized servicing
Choked gaps may cause failure of appliance.
8. Warranty
The manufacturer warranty is 24 months since the day of putting the apparatus into operation but not longer than 36
months since the day of purchase.
9. Disposal
The device contains electronic parts. It should be disposed in electronic-waste recycling centre according to the local
law.

ABB s.r.o.
EJF Organizational Unit
Vídeňská 117
619 00 Brno, Czech Republic
Tel.: [phone]
[phone]
Fax.: [phone]
E-mail: [email protected]
http:\\www.abb.com
The data and ilustrations in this catalogue are not binding.
We reserve the right for making changes to the content
in the course of technical development of the product.
1VLM000651,Rev.3, en 2014.01.21