Maintenance   
9.2 Inspection and maintenance 
  1LA5/6/7/9, 1LG4/6, 1MA6/7, 1MB..1/2/3/4/5 - SH 63 ... 355 
120  Operating Instructions, 06/2018, A5E44455710A 
 
If there are condensation drain holes present, open these at regular intervals, depending on 
climatic conditions. 
 
The winding can be damaged if objects are introduced into the condensation holes 
(optional). This can lead to death, serious injury or material damage. 
Note the following to maintain the degree of protection: 
•  Switch off the machine so that it is in a no-voltage condition before you open the 
condensation drain holes. 
•  Close the condensation drain holes, e.g. using T-plugs, before commissioning the 
machine. 
 
Reduction of the degree of protection 
If condensation drain holes are not closed, then this can result in material damage to the 
motor. 
In order to maintain the degree of protection, after the condensation has been drained, you 
must close all of the drain holes. 
 
Insulation resistance and polarization index 
Measuring the insulation resistance and polarization index (PI) provides information on the 
condition of the machine. It is therefore important to check the insulation resistance and the 
polarization index at the following times:   
●  Before starting up a machine for the first time 
●  After an extended period in storage or downtime 
●  Within the scope of maintenance work 
The following information is provided regarding the state of the winding insulation: 
●  Is the winding head insulation conductively contaminated? 
●  Has the winding insulation absorbed moisture? 
As such, you can determine whether the machine needs commissioning or any necessary 
measures such as cleaning and/or drying the winding: 
●  Can the machine be put into operation? 
●  Must the windings be cleaned or dried? 
Detailed information on testing and the limit values can be found here: 
"Testing the insulation resistance and polarization index"  (Page 90)