Power Electronics Training System (8032)


8837-Ax - IGBT Chopper / Inverter


 

 

 

 Release date:    2008-12-02

Affected model:      8837-Ax   –    IGBT Chopper / Inverter

Symptoms:     Random overcurrents and overheats may be detected by the module 8837-Ax when pulse signals, from the 9029‑00 (Chopper/Inverter Control Unit) or the 9030-30 (Thyristor Firing Unit), are applied to the switching control inputs of this module.

Causes:     The propagation delay time, at the opening of the IGBTs, is a little bit longer than the dead time (2 μS) causing a momentary short circuit on the DC bus of the 8837-Ax.

Note:  Although momentary short circuits may happen on the DC bus, be advised that this problem cannot damage the circuit of the 8837-Ax.

How to fix:    To fix the problem, six resistors (R39, R40, R41, R42, R43 and R44) must be replaced on the printed circuit board.  To know the new values of these resistors and their locations on the printed circuit board, please, download the following pdf file which contains a detailed procedure that explains how to modify the IGBT Chopper / Inverter.

 


Download pf1063.pdf

8960-1x - Prime Mover / Dynamometer


Release date: 2008-08-27

Affected models: 8960-1x  -  Prime Mover / Dynamometer

 

Brief description of the problem:   

Speed output signal inaccuracy at low speeds.

 

Full description of the problem:  

When the 8960-1x is running counterclockwise at speeds between 0 and 600 rpm, the speed output signal does not vary accordingly to the nominal rate of 500 rpm / V.

 

How to fix:  

To fix this problem, two resistors (R59 and R77) have to be replaced on the printed circuit board (30350 rev. 2) which is located beneath the motor.  To know the new value of these resistors and where they are located on the printed circuit board, consult the table and figure below.

 

 

Identification

current resistor value

New resistor value

R59

1.0MΩ  1/4W  5%

22.0MΩ  1/4W  5%

R77

10.0kΩ  1/4W  5%

2.4kΩ  1/4W  5%

 

 

Note:  

This product fix is valid only for 8960-1x units that have the revision #2 of printed circuit board 30350.  Before you undertake this modification, look at the upper left corner of the printed circuit board (beside Transformer T1) to make sure that your 8960 1x has the a revision.  In the event that your 8960-1x has an older revision of printed circuit board 30350, contact us by Email at:  services@labvolt.com.  


Download PF1062.JPG