5. Assembly of the switchgear on site
5.6 Installation of the busbars
5.6.1 Preparation of the material
Before to fix the panels side by side be sure that the bushings are fixed according to the chapter 3.3.1 at page 9.
• Clean the insulation on the busbar sections with a soft, dry cloth, and check for insulation damage.
Remove greasy or adhesive dirt as described in section 7.3;
• Busbar connections:
- The silver plated surfaces of the connections must be cleaned with a metal-free non-woven cleaning cloth and thinly and by appling a thin layer of mechanical grease;
- The non-silver plated surfaces of the connections are either brushed with a wire brush, preserving the grease film, or cleaned with a metal-free non-woven cleaning cloth and evenly greased with a thin layer of mechanical grease;
• Prepare insulating covers 58 and lids 58.5 (figure 3, 67, 68) to suit the relevant busbar connections and thread them onto the busbar. (For insulated busbars only).
Figure 67: 12/17.5kV panels, installation of the busbars. The lower picture shows the installation at the busbar ends.
29 busbar bushing 58 insulating cover
58.1 support for cover (at end panels only) 58.5 lid
58.6 washer, ISO 7089 58.7 washer, 25mm diameter
Figure 68: 24 kV panels - Arrangement of the busbar and branch conductors at the busbar ends. In continuous busbars, the connections are similar, but without the lid holder 58.1 and without the spacer plate 3.5.
2 Branch conductor 3 Busbar section 3.5 Spacer plate 58 Insulating cover 58.1 Lid holder
58.5 Lid for insulating cover (58.6) Washer ISO 7089 58.7 Washer 25 mm diameter 163 M10 hexagon socket head screw 164 M10 nut
165 10mm spring washer
58.5 58.1 165 165 58 2 58.5 3
(58.6) 163 164 58.7
58.5 3.5 165 58 2 58.5 3
58.1 58.7 163 164(58.6) 2 165
165 3
(10)(10)
During assembly, cut out the insulating cover and lid to fit the cross-section of the feeder bar or busbar.
a) Arrangement for 1250 A branch current and 1600 or 2500 A busbar current.
b) Arrangement for 2500 A branch and busbar current.
5.6.2 Busbar compartment access
Access to the busbar compartment is possible either from the top of the panel after dismounting the pressure relief plate 1.1 (figure 2) before the mounting of the gas duct, or from the front of the circuit-breaker compartment.
After circuit-breaker 13 (figure 2) has been with-drawn from the panel, it is possible to dismount horizontal partition 20 by unscrewing nr.4 screws holding the partition from the inside.
After that, the partition 9 can be dismantled (by unscrewing nr.7 screws) and taken out of the panel, which makes access to busbars from the circuit-breaker compartment possible.
Figure 69: accessing busbar compartment
5.6.3 Busbars installation
• Install the busbars panel by panel according to the ratings of the switchgear (figures 70÷77). Screw on the individual busbar elements one above the other (depending on the system layout) and in line with the flat branch conductor.
For the tightening torque please make reference to the table at page 40. Use two dished washers for each screw. Use screws of tensile class 8.8.
• Bolt one holder 58.1 (figure 67, 68) to each end of the busbars to support insulating cover 58. The screws for holder 58.1 must be tightened with a lower torque. (For insulated busbars only).
• Position insulating covers 58 and lids 58.5 over the relevant bolted joint, and slide the lid onto the cover until it clicks into place. (For insulated busbars only).
Note:
Busbar connection is carried out with so-called “stabilized connections”.
This means that quality of the copper busbar connections does not change according to the operating time and therefore it is not necessary to inspect tightness of busbar connections regularly. But this is on condition that correct assembly is carried out as described above and especially that all connections are tightened with the prescribed torque according to the above table.
We recommend only inspecting tightness of busbar connections during inspections (see chapter 7).
9 20
5.6.3.1 Busbars for 12/17.5kV units
Busbars are made of copper and have a flat cross-section for rated current up to 2500A. For 3150, 3600 and 4000A, the busbars have a double D-shaped cross-section. Branch conductors always have a flat cross-section.
12/17.5kV bushings are made of epoxy resin castings and are arranged as a single casting for all three phases (figure 61). For bus-tie units the bushings are single and are arranged in the lower part of the unit. Bushings are held in bushing plates.
For 12 kV, the busbars are bare (without insulation) and without insulating covers up to 2500A.
3150, 3600 and 4000A D-shaped busbars are insulated by means of shrink sheaths and are fitted with insulating covers.
For 17.5 kV, the busbars are insulated and fitted with covers over the whole current range.
Figure 70: 12/17.5 kV panels – Tee-off 630-1250A, busbars 1250A 40 nr. 4 10x35 screws
42 nr. 8 M10 washers 43 nr. 4 M10 nuts
Figure 71: 12/17,5 kV panels – Tee-off 630-1250A, busbars 1600A-2000A-2500A 41 nr. 4 10x60 screws
42 nr. 8 M10 washers 43 nr. 4 M10 nuts 44 nr. 1 spacer (15mm)
40
42
43
41
42
43
44
Figure 72: 12/17.5 kV panels – Tee-off 1600-2000A-2500A, busbars 1600A-2000A-2500A 41 nr. 4 10x60 screws
42 nr. 8 M10 washers 43 nr. 4 M10 nuts 45 nr. 1 spacer (5mm)
Figure 73: 12-17.5 kV panels – Tee-off 630-1250A, busbars 3150A-3600A-4000A 4 nr. 4 10x60 screws
42 nr. 8 M10 washers 43 nr. 4 M10 nuts 44 nr. 1 spacer (15mm)
41
42
43 45
41
42
43 44
Figure 74: 12-17.5 kV panels – Tee-off 1600÷4000A, busbars 3150A-3600A-4000A 41 nr. 4 10x60 screws
42 nr. 8 M10 washers 43 nr. 4 M10 nuts 45 nr. 1 spacer (5mm)
5.6.3.2 Busbars for 24 kV units
Busbars and branches are made of copper and both have a flat cross-section. Bushings are different from the 12/17.5kV ones. They are single for each phase and have an electrode inside, which must be connected to the busbar.
Busbars for 24 kV units are insulated by means of shrink sheaths and the connection points are covered by insulating covers.
41
42
43 45
- 1250 A - 1250 A
41 42
43
Figure 75: 24 kV panels – Tee-off 1250A, busbars 1250A 41 nr. 4 10x35 screws
42 nr. 8 M10 washers 43 nr. 4 M10 nuts
- 1250 A - 2500 A
- 2500 A - 2500 A
Figure 76: 24 kV panels – Tee-off 1250A, busbars 2500A 41 nr.4 10x60 screws
42 nr.8 M10 washers 43 nr.4 M10 nuts
Figure 77: 24 kV panels – Tee-off 2500A, busbars 2500A 41 nr.4 10x60 screws
42 nr.8 M10 washers 43 nr.4 M10 nuts
41 42
43
41
42
43
Important note:
Always check that there is good contact between the metal tube in the bushing and the busbar via contact spring 29.3. Ensure that the contact spring is in the correct position! (figure 78).
Figure 78: 24 kV panels - detail of the busbar bushing, sectional view
3 Busbar
29 Busbar bushing
29.2 Busbar support for double conductor 29.3 Contact spring
29.4 Metal tube
Important note:
The contact springs 29.3 must be inserted
during the installation of busbars. These contact springs make the connection between the busbar 3 and the metal tube 29.4 and prevent damage caused by partial discharges inside the bushing on live busbars.
Always check that there is good contact between the metal tube 29.4 in the bushing and the busbars via the contact spring.
5.7 Installation of the top-mounted boxes
For transport reasons, attachments to the panels are not completed at our works. However, they are pre-mounted as far as possible.
5.7.1 Voltage transformer for busbar metering
• Top-mounted box 79 (figure 81) with screw fixing material in the set of bags “Top-mounted box for metering” must be mounted on the busbar compartment.
Notes
- In panels without busbar bushing plate 28, the partition between the busbar compartment and the top-mounted box is necessary. They are installed at the works in the top-mounted box;
- As far as equipment with busbar partitioning is concerned (i.e. with bushing plate 28), the space between the busbar compartment and the top-mounted box must remain open for purposes of pressure relief;
• Connecting bars 2.2 with branch conductors 2 at the junction point must be screwed together according to figures 79 and 80. However, if necessary, the additional spacer plate 3.2 or 3.3 and threaded plate 3.4 or 3.8, as well as the screw fixing material from the “top-mounted box for metering”
set of bags must be used;
• Insulating cover 58 must be brought into position as is described in section 5.4;
• Intermediate box 79.1, with the screw fixing material from the “top-mounted box for metering” set of bags must be mounted on the control cabinet. Conduction tube 79.2 must be positioned and inserted in reducer rings 79.3;
• Secondary circuits from the voltage transformers must be led to the terminal strips and connected according to the cable core markings and circuit diagram.
Figure 79: 12/17.5kV panels - Bar connection to the top-mounted box. The figure shows the arrangement in panels the busbar ends
2 Branch conductor 2.2 Connection bar
3.2 Spacer plate, 5 mm thick 3.8 Tapped plate
3.10 Spacer plate, 8 mm thick
3.2 2.2
3.2 3.8
58.5 3.5 (58.6) 3.4 58 162 2.2 58.5 3
58.1 58.7 (35)
165 2 3
163
3.3 3,4 162 2.2
(10)
3.3
35
2432 80
70
M10 35
5032
15 3.4
25
2432 80
3.5 58.1 58.7 163 (58.6) 165 2 3
Figure 80: 24 kV panels - Bolted busbar joint for top-mounted box, shown for left-hand busbar end. In continuous busbars is the connection is similar, but without the lid holder 58.1 and without the spacer plate 3.5.
2 Branch conductor
2.2 Branch conductor to the top-mounted box 3 Busbar section
3.3 Spacer plate, 10 mm thick 3.4 Threaded plate
3.5 Spacer plate 58 Insulating cover 58.1 Lid holder
58.5 Lid for insulating cover (58.6) Washer 2 mm
58.7 Washer 3 mm 162 Cylinder screw
163 M10 hexagon socket head screw 165 10 mm spring washer
Figure 81: 12/17.5kV panels - Top-mounted box with voltage transformers for busbar metering. The figure shows the arrangement in panels without the busbar bushing plate 28 (see the notes in section 5.7.1)
28.3 Partitioning
79 Top-mounted box with voltage transformer 79.1 Intermediate box
79.2 Conductor tube 79.3 Reducer ring
Figure 82: 24 kV panels - Top-mounted box with high voltage transformers for busbar metering. The figure shows the arrangement in panels with busbar bushing plate 28 and bushings 29
2.3 Flat branch conductor for voltage transformers 28 Bushing plate
79 Top-mounted box for busbar voltage transformers 79.1 Intermediate box
79.2 Conductor tube 79.3 Reducer ring 79.4 Pressure relief
79.4
79
2.3
28
79.2 79.3 79.1
79.2 79.3 79.1
79
28.3
5.7.2 Earthing switch for busbar earthing
• Top-mounted box 77 (figure 83) with screw fixing material from the “top-mounted box for earthing”
set of bags must be mounted on the busbar compartment;
• Operating mechanism box 78 with screw fixing material from the “top-mounted box for earthing” set of bags must be mounted on the control cabinet;
• Pre-mounted single parts of hexagonal shaft 78.1 must be removed. Pay attention to the sequence and angling of the parts!,
• Hexagonal shaft from the operating mechanism box must be pushed through into the bevel gear of the earthing switch. Sequence and angles of the part must be restored!
• Connecting bars 2.2 with the branch conductors 2 at the junction point must be screwed together according to figure 5/26 and 5/34. However, if necessary, additional spacer plate 3.3 or 3.2 and threaded plate 3.4 or 3.8, as well as the screw fixing material from the “top-mounted box for earthing”
set of bags must be used;
• Insulating cover 58 must be brought into position as described in section 5.4.
Note
The auxiliary switches for the earthing switch are adjusted at the works. Problem-free operation is only guaranteed if the working elements on the hexagonal shaft are correctly mounted.
Because of final installation of the earthing switch and operating mechanism on site, it may be necessary to make precise adjustment of the auxiliary switches.
In that case, the following is important:
• The auxiliary switch OFF 78.5 must be operated:
- before slide 78.2 has uncovered half of the opening in front of the hexagonal shaft and;
- before the lower edge of the slide has touched the anchor of locking magnet 78.6;
• The auxiliary switch ON 78.4 must be operated:
- before the toggle spring of the earthing switch has reached its dead centre point;
• The push-rod of the auxiliary switch must still have about 0.5 mm to go to the end position in the operated position.
77
78.1
78
Figure 83: 12/17.5kV panels - Top-mounted box with earthing switch for busbar earthing 77 Top-mounted box for top-mounted 78.4 Auxiliary switch ON
earthing switch 78.5 Auxiliary switch OFF
78 Operating mechanism box 78.6 Locking magnet 78.1 Operating shaft
78.2 Slide
2.2
77 78.1 78
Figure 84: 24 kV panels - Top-mounted box with earthing switch for busbar earthing. The arrangement is the same as the figure above
2.2 Flat branch conductor for earthing switch 77 Top-mounted box for earthing switch 78 Operating mechanism box
78.1 Hexagonal shaft
5.8 Pressure relief ducts
The standard solution provided for the arc-proof version of the UniGear ZS1 consists of a metal sheet duct for collecting and exhausting the hot gases; this duct is mounted on the upper side of the switchgear and normally it is extended on both the right and left extremities
This solution is capable to guarantee the safety for the persons that are standing in front of the switchgear, according to the IEC 62271-200 Standard (criteria 1 to 5).
The recommended solution in order to avoid the exhausting of the gases and the overpressures inside of the switchgear installation room is to prolong the exhaust duct outside of the substation (from left and right sides or front and rear sides). In this case, take care of the accessibility of the persons in the gas-exhausting zone and protect the gas exhaust channel extremity in order to avoid the entrance of water, dust, small animals and any foreign object.
UniGear ZS1 switchgear is available with the following solution of gad duct:
• Standard duct;
• Compact duct;
• Compact duct with top chimneys.
The pressure relief duct is supplied dismantled in single parts. The rear and front wall correspond, as far as length is concerned, with the appropriate panel width. They are joined together by means of the attachment strips.
The screw fixing material is contained in the “pressure relief duct” set of bags. Rivet nuts are already provided in the metal sheets.
Note
The rear pressure relief flap must be mounted according to figure 85.
Details regarding connection to the wall and a discharge grating for pressure relief outside the switchroom will be agreed on with the customer.
Figure 85: Schematic diagram of the pressure relief duct. The components are assembled panel by panel and bolted together with overlaps at the panel joints.
50 pressure relief duct
1) If the switchgear is equipped with a pressure relief duct, the pressure relief flap for the cable connection compartment is fixed to the rear side of the panel and will open to the front (into the duct) in case of an arc fault.
5.8.1 Standard gas duct
Once that the panels are fixed between them and to the floor, it is possible to start to fix the gas duct on the top of the switchgear. Every panel have three fixing points in the front part (figure 86) and three fixing points on the rear part (figure 87).
Figure 86: Fixing points on the front.
With nr. 6 screws 8x20 and nr. 6 washer M8, fix the front and rear part of the gas duct sheets (figures 88, 89).
Figure 87: Fixing points on the rear.
Figure 88: Front sheet. Figure 89: Rear sheet.
1)
50
Once that the two sheets are fixed to the panel, it is possible to fix the two sheets between them (figure 90) using nr.6 screws.
Figure 90: Junction of the front and rear sheet.
Nr. 6 screws 10x30 Nr. 6 M10 nuts Nr. 12 M10 washer
Repeat the above described operations for the adjacent panel.
At this point it is possible to fix the front connection plate between the two gas duct panels (figures 91).
Figure 91: Front connection plates.
Nr. 8 screws 8x30 Nr. 8 M8 washer
Fix the central connection plate between the two gas duct panels (figures 92).
Figure 92: Central connection plates.
Nr. 10 screws 8x30 Nr. 10 M8 washer
Fix the rear connection plate between the two gas duct panels (figures 93).
Figure 92: Rear connection plates.
Nr. 8 screws 8x30 Nr. 8 M8 washer
Repeat the above described operations for all the panels.
The next operation is the fixing of the left and right end side (figures 93).
Figure 93: Side plates.
Nr. 13 screws 8x30 Nr. 13 M8 washer
The last operation in order to complete the gas duct is the fixing of the gas duct extension on both sides (figure 94).
Figure 94: Side plates.
Nr. 10 screws 8x30 Nr. 10 M8 nuts Nr. 10 M8 washer
Figure 96: Overview of the compact gas duct.
Figure 95: Overview of the standard gas duct.
5.8.2 Compact gas duct
In order to mount the compact gas duct must be followed the operations described for the standard gas duct.
5.8.3 Compact gas duct with top chimneys
In order to mount the compact gas duct with top chimneys must be followed the operations described for the compact gas duct.
The difference between the two solutions is that in this case there are no side exits, but the gas generated from an internal arc goes out from the duct through the top chimneys located on the top part of the gas duct on each panel.
On the top of the gas duct there are two openings (figure 97); for each opening it must be fix the net and the nr.6 spacers (figure 98).
At this point it is possible to fix the top cover with nr.12 M8 screws.
Figure 99: Top cover of top chimneys.
Figure 97: Openings on top of the gas duct. Figure 98: Net and spacers of top chimneys.
5.9 Cable connection
5.9.1 Power cables
The standard method for entry of power cables in the switchgear is shown in Figures 100, 101.
The cables are conveyed from below through floor covering 17, which is divided at the cable entry point.
The cables go through rubber reducer rings 17.2, which can be adapted to the required cable diameter in a range from 27 to 62mm. Cables are fastened in the panel by means of cable clamps mounted on cable strips, which are part of the panel floor covering. The clamps make it possible to fasten cables with diameters between 35 and 54mm.
Cable sealing ends are mounted on the cable cores according to the manufacturer’s instructions. It is possible to use cable sealing ends of different manufactures (e.g. Pirelli, Raychem etc.), but it is necessary to keep the length of the cable ends, including cable sealing ends, which is given by the distance of cable connecting bars 23 from the panel floor covering.
These bars have different versions, hich differ in their number of parallel cables and the values of rated and short-circuit currents. See ig. Figure 102÷106.
The bars are equipped with holes for M16 screws. If M12 screws are used for cable connections, special washers with the diameter for M12 screws must be used. In all cases, the earthing of cable screens is carried out on the strip-holding cable clamps. The cable strip is connected to the earth potential.
It is also possible to place the removable arrangement of voltage transformers in the cable compartment. These can be fitted with HV fuses similar to those in the measuring panel. Three fixed mounted surge arresters can also be installed here. But in both these cases the number of parallel cables must be reduced – see the table.
The cable connections bars are equipped with holes for M16 screws, but they are supplied without screws, washer and nuts.
The supply of this material, according to the cable termination, is at Customer charge.
Figure 101: Partial view of the cable compartment, prepared here for connection of triple cables.
39 Mounting rail, connected to earth potential
Figure 100: View into the cable connection compartment, max. six parallel cables are possible
6.1 Earthing switch position indicator 17 Floor cover, split
Range Connection of cables in typical panels:
1) In the case where there are removable voltage transformers on the truck, or surge arresters are used, the number of parallel cables is reduced to a max. of 2 per phase.
2) In the case where there are removable voltage transformers on the truck, or surge arresters are used, the number of parallel cables is reduced to a max. of 4 per phase.
Cable connection in the panel with switch-disconnector Range
Connection with single-core plastic insulated cables is presumed in the typical panels. In the case of any atypical cable connections or of special cables (e.g. three-core cables, cables with paper or special insulation etc.), an agreement must be reached between the customer and manufacturer.
Mounting procedure for power cables:
• Power cables must be inserted, cut to length and stripped;
• Reducer rings 17.2 (figure 100) must be adapted to the cable diameter and fitted onto the cable;
• Cable sealing ends must be prepared and mounted on cable cores according to manufacturer’s
• Cable sealing ends must be prepared and mounted on cable cores according to manufacturer’s