Basler Electric BE1-11m - Manual (Page 537)

9424200996 Rev L 525
Figure 349. Protection, Thermal, RTD Bias Curve Screen
Set the Center RTD Bias Temperature (point 2) to the motor hot running temperature. Recall from the
motor manufacturer data that the insulation is class F and the manufacturer allows an 80
°C stator
temperature rise. Allow for a 10 percent overage for hot spots. Refer to the Center RTD Bias Temperature
Equation 41.
𝐶𝑒𝑛𝑡𝑒𝑟 𝑅𝑇𝐷 𝐵𝑖𝑎𝑠 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 = �𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒
𝑅𝑖𝑠𝑒 𝑜𝑓 𝑆𝑡𝑎𝑡𝑜𝑟
∙ 10% 𝑜𝑣𝑒𝑟𝑎𝑔𝑒� + 𝐴𝑚𝑏𝑖𝑒𝑛𝑡 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒
= (80°𝐶 ∙ 1.10) + 40°𝐶
= 88°𝐶 + 40°𝐶 = 128°𝐶
Equation 41. Center RTD Bias Temperature
A good starting point for the center point Thermal Capacity (%TC) is the percentage difference between
the Hot Safe Stall Time and the Cold Safe Stall Time. This point can be modified later after observation
and motor monitoring. The initial calculation for %TC is given in Equation 42.
%𝑇𝐶 = 100% �1 −
𝐻𝑜𝑡 𝑆𝑎𝑓𝑒 𝑆𝑡𝑎𝑙𝑙 𝑇𝑖𝑚𝑒
𝐶𝑜𝑙𝑑 𝑆𝑎𝑓𝑒 𝑆𝑡𝑎𝑙𝑙 𝑇𝑖𝑚𝑒
�
= 100% �1 −
9
10� = 10 %𝑇𝐶
Equation 42. Center Point Thermal Capacity
Set the Center RTD Bias Temperature (point 2) to 128
°C and 10 percent thermal capacity per the results
from Equation 41 and Equation 42.
The Maximum RTD Bias Temperature (point 3) is set to 155
°C and 100 percent thermal capacity. These
values are determined by the maximum insulation factor of F according to the motor manufacturer data.
Resistance Temperature Detector (49RTD)
The RTDs can be used as a direct source for protection as well. The maximum stator winding insulation
temperature is 155
°C per the motor manufacturer data.
Set the 49RTD-1 protection element as shown in Figure 350 to protect the stator winding insulation.
Voting is set to 2, meaning at least 2 RTDs must be at 155
°C or higher to result in a trip. A delay is not
required for the reason that temperatures change slowly because of the large motor thermal mass.
BE1-11m Settings Calculation Examples