Chapter 6 Optional Accessories | VFD-ED
5. The selection tables are for normal use. If the AC motor drive requires frequent braking, increase the Watts by
two to three times.
6. Thermal Overload Relay (TOR):
Thermal overload relay selection is based on its overload capacity. A standard braking capacity of the VFD-ED
is 10%ED (Tripping time = 10s). As shown in the graph below, a 460V, 11 kw VFD-ED requires the thermal
relay to take 260% overload capacity for 10 seconds (hot starting) and the braking current is 17.7 A. In this
case, select a thermal overload relay larger than 17.7 / 2.6 = 6.8 (A). The specification of each thermal relay
may vary among different manufacturers. Carefully read the specification before using it.
Figure 6-3
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