TBBZ High Voltage Automatic Compensation Assemblies
Description
Automatic compensation on 6kV and 10kV feeders
TBBZ assemblies provide automatically switched high-voltage shunt capacitor compensation on overhead distribution circuits. Applications include 6kV and 10kV feeders, small terminal substations and local compensation of high-voltage motors. The integrated assembly includes capacitor units, a capacitor-duty vacuum contactor, drop-out fuses, voltage and current transformers, zinc-oxide arresters and an automatic compensation controller.
System ratings and service limits
Parameter
Specification
Rated system voltage
6kV or 10kV
Maximum operating voltage
6.6kV or 11kV respectively
Frequency
50Hz
Permissible steady overvoltage
1.1 times rated voltage
Permissible steady overcurrent
1.3 times rated current
Capacitance deviation
0 to +5%
Discharge
Each capacitor group below 50V within 10 minutes after disconnection
Altitude
≤1000m
Ambient temperature
-40°C to +45°C
Wind speed
≤35m/s
Seismic intensity
≤8
Solar irradiance
≤0.1W/cm²
External insulation creepage
≥2.5cm/kV
Installation inclination
≤5°
Environment
No harmful gases or vapour and no conductive or explosive dust; site harmonics must satisfy the applicable system requirements
Reference standards
JB/T7111-1993; DL/T604-1996
10kV model configurations
System voltage and capacitor-group voltage are separate selection fields. Retain both when specifying a model, because the same TBBZ output designation is used in different voltage configurations. For U/√3 capacitor configurations, the capacitance column represents the phase capacitor value; use it with the matching connection and capacitor voltage.
No.
Model
System voltage (kV)
Capacitor-group voltage (kV)
Rated output (kvar)
Rated current (A)
Capacitance (µF)
1
TBBZ-100
10
10.5
100
5.5
2.87
2
TBBZ-200
200
11
5.77
3
TBBZ-300
10.5/√3
300
16.5
8.66
4
TBBZ-360
360
19.8
10.4
5
TBBZ-450
450
24.7
12.99
6
TBBZ-600
600
33
17.32
7
TBBZ-900
900
49.4
25.98
8
TBBZ-1200
1200
65.9
34.65
6kV model configurations
No.
Model
System voltage (kV)
Capacitor-group voltage (kV)
Rated output (kvar)
Rated current (A)
Capacitance (µF)
9
TBBZ-100
6
6.3
100
9.2
8.02
10
TBBZ-200
200
18.3
16.04
11
TBBZ-300
300
27.5
24.06
12
TBBZ-360
360
33
28.87
13
TBBZ-450
6.3/√3
450
41.2
36.09
14
TBBZ-600
600
54.9
48.12
15
TBBZ-900
900
82.4
72.18
16
TBBZ-1200
1200
110
96.24
Protection functions and settings
Protection options include short circuit, overcurrent, overvoltage, undervoltage, voltage loss and phase failure. Capacitor closing is inhibited during the fixed 10-minute discharge interval. Protection thresholds and delays can otherwise be selected for the installation.
Protection
Setting or action
Delay
Main-circuit phase-to-phase short circuit
Drop-out fuse clears the faulted phase; vacuum contactor trips
0.2-0.5s contactor delay
Capacitor phase-to-neutral short circuit
3 times rated current
Capacitor-bank overcurrent
1.4-1.5 times rated current
5s
Overvoltage
1.1-1.3 times rated voltage
20-30s
Undervoltage
0.6 times rated voltage
0.2-0.5s
Voltage loss
Trip on loss of supply voltage
Phase failure
Phase-loss trip, selectable
—
Lightning overvoltage
Zinc-oxide arrester
—
Switching overvoltage
Capacitor-duty zinc-oxide arrester
—
Capacity allocation and feeder position references
The following analytical reference gives the share of total compensation assigned to the substation and feeder, with a position parameter expressed as a fraction of main-feeder length. Final selection depends on the actual load distribution, site access, environment and maintenance arrangements; these idealized loss reductions are planning values.
Reactive load distribution
Feeder capacitor groups
Share of total compensation
Position parameter
Calculated line-loss reduction
Substation
Feeder
Uniform
1
1/3
2/3
2/3
88.90%
2
1/5
4/5
2/5 and 4/5
96%
Increasing along the feeder
1
0.2
0.8
0.775
93%
Decreasing along the feeder
1
0.374
0.626
0.442
86.40%
Isosceles distribution along the feeder
2
0.204
0.796
0.554
91.70%
Configuration and installation
Equipment, contactor, voltage, output and controller configuration fields.Support and clearance references for the illustrated overhead-line installation.
