Lenze i700 - Manual (Page 247)

Lenze · i700 servo inverter · Reference manual · DMS 1.5 EN · 03/2014 · TD05
247
8 Monitoring functions
8.4 Monitoring of the motor utilisation (I²xt)
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The speed-dependent evaluation of the permissible motor current can actually be switched off by
parameterising all 8 characteristic points to "100 %".

Stop!
Applications with standard motors
Self-ventilated standard motors are insufficiently protected at low speeds if the speed-
dependent evaluation of the permissible motor current is not effective (all characteristic
points = "100 %").
Applications with PM synchronous motors
Please check for every individual case which r.m.s. value can be used to permanently
operate the motor at standstill.
In case of some motors, a derating I1/In < 100 % is required when n1/nn = 0 %. This
serves to prevent an overload of individual motor phases as their power loss doubles
with continuous DC current load. (It is called DC current load as the field frequency
amounts to 0 Hz at standstill.)