User`s guide

LONWORKS LPT-10 Transceiver User’s Guide 5-9
Power Specifications for Extended Performance
Although more complex, this alternative power specification allows for extended
power performance. In addition, it features a separate derating for the average wire
temperature.
I is the average application current of a node. The distance of an LPT-10 transceiver
from the LPI-10 module is the node distance, d. For each branch, the sum of the products
of a node distance and the application current of that node must not exceed a constant:
I
1*
d
1
+ I
2*
d
2
+ I
3*
d
3
+ . . . ≤ K
*
α
*
β
where
K is the nominal value, dependent on wire type:
K=1400 Amp*Meters for Belden 85102 and Belden 8471, 16 AWG
K=530 Amp*Meters for JY (St) Y 2x2x0.8
K=370 Amp*Meters for Level 4/ 22AWG
α =
1
1 + 0.00393
*
(temp - 25°C)
, accounting for average wire temperature
β= 81%, derating for manufacturing and all other variations
At 25°C, α = 1. Note that α is greater than one when average wire temperature is less
than 25°C and is less than one when the temperature is greater than 25°C.