To Verify Temperature Rise of Assembly, following are the ways, as per IEC 61439 :
- Testing with Current
- Derivation from Tested design
- Calculation
Here we will see, Testing with Current :
How to verify Temperature Rise of ASSEMBLY ?
- Select the Arrangement as in normal use
The Test shall be done on Switchgear and Panel arrangement which is as in normal use for load combinations choosen with highest possible Temperatuer rise. Including all the Covers, Doors etc closed as in normal use.
- Select Busbar with greatest cross section shall be selected as in normal use
Busbar arrangement in HBB, VBB may be consisting of single or multiple busbar sections.
- Select Functional Unit Switchgear as in normal use.
Various Functional Units with Switchgear complete with all power and control connection to be selected as in normal use. Switchgear power loss palys important factor in this test.
- Temperature Rise test on various circuits shall be made with their intented rated current.
Incoming and outgoin Feeders shall be loaded with their rated currents. Temperature Rise test need to be made till the Temperature rise reach a constant value, 1 °K/hour. Generally it takes 8 to 9 hours.
- Temperature Measurement
Temperature shall be measured at various points in Assembly, including Switchgear, busbar and Joints.
- Ambient Air Temperature
Ambient Air Temperature in the Room where test Assembly is put, shall be measured at 1 meter from Assembly and the same shall be +40 °C.
- Temperature Rise Limits
At the End, Temperature rise above Ambient Temperature(35 °C-24 hour meam) shall not exceed following :
1) Switchgear Temperature Rise as per Switchgear Manufacturer.
2) Terminals for Incoming/Outcoing Cable : < 70 °K Rise
3) Temperature Rise of Busbar is limited by mechnical Strength of busbar material, permissible temperature rise of Insulating Busbar supports, and effect of Switchger connected to Busbar.
At Switchgear Terminals < 85 °K Rise
At Busbar Joints < 90 °K Rise
Above Are max Limits, Actual Rise are to be defined by Manufacturer.
4) Insulated Operating Hangle < 25 °K Rise
5) Assembly External Metal Surface < 30 °K Rise