The range of the IEEE Std 1584 model is as follows (as per the 2002 edition of the standard)...
- Voltages in the range of 208 V-15 000 V, three-phase.
- Frequencies of 50 Hz or 60 Hz.
- Bolted fault current in the range of 700 A-106 000 A.
- Grounding of all types and ungrounded.
- Equipment enclosures of commonly available sizes.
- Gaps between conductors of 13 mm-152 mm.
- Faults involving three phases.
I have a few questions regarding the above...
1) I understand that the Lee Method can be used for voltages over 15 kV, should it also be used for voltages under 208 V?
2) Section 5.4 of IEEE Std 1584-2002 mentions that the Lee Method can also be applied where gap is outside the range of the model. Can the Lee Method also be applied when other parameters (apart from voltage and gap) fall outside the range of the IEEE Std 1584 model (e.g. a frequency of 400 Hz, or bolted fault currents less than 700 A or exceeding 106 kA)?
3) The model is applicable for gaps between conductors of 13 mm-
152 mm. However, Table 4 of IEEE Std 1584-2002 lists typical gap between conductors for system voltages >5-15 kV of...
- 13 mm-153 mm for open air equipment
- 153 mm for switchgear equipment
Interestingly, Table 2 lists a typical bus gap of
152 mm for 15 kV switchgear.
I realise that 1 mm is a very small difference, but is the 153 mm a mistake (I'm unable to find any published errata to confirm this) or is there some reason why a value outside of the model is specified in Table 4?
Any input would be much appreciated.
Clive
