Guideline
1 (2)
unofficial translation
Transmission Service
15.2.2007
STANDARD RATED VALUES OF THE GRID
RATED VOLTAGE, kV
110
400
MAXIMUM PERMITTED OPERATING VOLTAGE, kV
INSULATION LEVELS OF SUBSTATIONS
Minimum impulse test voltage (both polarities), kV
- phase-to-earth
- clearance between open contacts
Minimum switching test voltage (dry and wet, both polarities), kV
- phase-to-earth
- clearance between open contacts
Minimum test voltage at 50 Hz frequency (dry), kV
- phase-to-earth
- clearance between open contacts
REQUIRED MINIMUM OPERATING TEMPERATURE OF APPARATUS
In Southern and Western Finland, ºC
In Northern and Eastern Finland, ºC
INSULATION LEVELS OF OVERHEAD LINES
Minimum impulse test voltage, kV
Minimun switching test voltage, kV
Minimum 50 Hz test voltage in one minute rain test, kV
Minimum creepage distance, mm
FLASHOVER DISTANCE ON INSULATOR STRING (clearance of arcing horns)
suspension string, mm
tension string, mm
PHASE-TO-PHASE SPACING OF AN OVERHEAD LINE
Minimum phase-to-phase spacing, m
123
420
550
630
1425
1425(+240)
-
1050
900 (+345)
230
265
520
610
-40
-50
-40
-50
450
230
1960
1300
1050
6720
RADIO INTERFERFENCE TEST VOLTAGE, kV
)
870...890 2700...2750
1000..1020 2900...2950
4,0
1,1
8,5
123
3
1,1
420
3
RADIO INTERFERFENCE, CORONA AND ELECTROMAGNETIC FIELDS
Equipment and installations shall be designed and implemented so that corona and other electrical discharge and
radio interferences are minimized and do not exceed levels measured according to publicaation IEC - CISPR 18.
For radio interferences requirements are as follows at 0,5 MHz frequency and at 20 m distance from outermost
equipment or phase conductor:
At substations (fair weather/rainy weather)
< 60/75 dBm (µV/m)
On power lines (fair weather/rainy weather)
< 50/65 dBm (µV/m)
Sound level shall not exceed by the side of the fence of substation and for power lines at distance of 20 m from
the outermost phase conductor on fair weather the value of 45 dB (A) and on rainy and hoar-frost generating
weather the value of 65 dB (A).
The substation switchgears and busbar systems shall be designed so that maximum permissible exposure
values of electromagnetic field are not exceeded at substation area at height 1 m of the ground. Electric field
strength shall not exceed 10 kV/m nor shall magnetic field strength exceed value 500 T, unless stay on such
areas is obstructed.
CURRENT-CARRYUNG CAPACITIES
Load rating and fault current rating requirements will always be defined on a case by case basis.
The value put in brackets is the peak value of alternating voltage on opposite pole while testing the clearance between open
contacts.
Voltage distance and creepage distance of a tranposition string shall be at leat 1,7 -fold compared to standard suspension string.
If phase conductors lie vertically over one another will phase-to-phase distance be determined according to
"vahvavirtailmajohtomääräykset" (= "Overhead power line regulations" in Finnish).
Guideline
unofficial translation
Transmission Service
15.2.2007
Required minimum operating temperature of apparatus
2 (2)