TES have over 50 years of experience, designing and building all types of Switchboards and Motor Control Panels including Forms 1, 2, 3B & 4B. We have also acquired Cubic Accreditation as Switchboard Designers and Builders to AS/NZS 61439 for the following:
- A = Assemblies up to 3200 A
- B = Assemblies above 3200 A
- C = Draw Out/Plug-In – Motor Control Devices
- DV = AS/NZS 61439 Design Verification
What are the main differences between AS/NZS 3439 (old) and AS/NZS 61439 (new)?
|Area of Difference||AS/NZS 3439 (Old)||AS/NZS 61439 (New)|
|Term for a compliant switchboard||Type Test (TT) & Partial Type Test (PTT)||Design Verified (TT & PTT no longer used)|
|Heat rise testing||May be undertaken in “Free Air”||Must be completed as a complete system 1)|
|Temperature limits of copper conductor||ΔT of 70K above a mean ambient of 35°C||ΔT of 105K from a mean of 35°C
Therefore, a maximum theoretical mean of 140°C on the copper 2)
|Heat rise calculation using IEC 60890||Allowed up to 3150A||For a single compartment ASSEMBLY not exceeding 630A or for ASSEMBLIES not exceeding 1600A|
1) Testing with all covers fitted and electrical components connected.
2) ΔT of 105K is specified in the standards as this is the maximum temperature rise before copper starts to anneal. This theoretically could allow a maximum absolute temperature of 140˚C on the copper busbar. However, as under the new standard tests must be conducted as a complete system, other temperature limits will be reached before 140˚C on the busbar. For example electrical components terminal and air temperature limits.