mjaye65
Member
Greetings Guys,
I just finished a job where one of the things we did was replace the precharge resistors in a Siemens Inverter Drive.
In all that I know and have been taught when you replace a resistor or resistors all you have to do is match resistance value, and match or exceed Wattage rating.
In the job we just finished this prove not to be the case. There is something special about the manufacturing process of the Siemens resistor Siemens part number 6SX7010-0AC13. Description: Resistor, 2.7 Ohm, 10% Tolerance @ 110W, The MFG stamp on the resistors is R3 ZBS 30/215 2R7 10% WM110.
We did not have one of these on hand and what was supplied by our Buyers was a 3.1 Ohm instead of 2.7 Ohm, 210 Watt instead of 110 Watt, Wire wound Resistor instead of Flat wire bands with an acrylic coating encapsulating the entire resistor.
As soon as we restored power and closed the associated contactor feeding these resistors. The resistors turned into a dead short resulting in the 800 Volt contactor to weld closed. The resistors did eventually open and stop the current but the damage was done.
The purpose of the resistors is to limit current momentarily while the charging of a capacitor bank starts. Once the bank reaches 600 of the 800 VDC operating voltage another contactor closes and removes these resistors from the circuit and feed power to the capacitor bank a different way and completes the charging.
I have always received valuable information in this forum and I hope someone here as seen or used the Siemens resistors before and can tell me what is so special.
Thanks.
I just finished a job where one of the things we did was replace the precharge resistors in a Siemens Inverter Drive.
In all that I know and have been taught when you replace a resistor or resistors all you have to do is match resistance value, and match or exceed Wattage rating.
In the job we just finished this prove not to be the case. There is something special about the manufacturing process of the Siemens resistor Siemens part number 6SX7010-0AC13. Description: Resistor, 2.7 Ohm, 10% Tolerance @ 110W, The MFG stamp on the resistors is R3 ZBS 30/215 2R7 10% WM110.
We did not have one of these on hand and what was supplied by our Buyers was a 3.1 Ohm instead of 2.7 Ohm, 210 Watt instead of 110 Watt, Wire wound Resistor instead of Flat wire bands with an acrylic coating encapsulating the entire resistor.
As soon as we restored power and closed the associated contactor feeding these resistors. The resistors turned into a dead short resulting in the 800 Volt contactor to weld closed. The resistors did eventually open and stop the current but the damage was done.
The purpose of the resistors is to limit current momentarily while the charging of a capacitor bank starts. Once the bank reaches 600 of the 800 VDC operating voltage another contactor closes and removes these resistors from the circuit and feed power to the capacitor bank a different way and completes the charging.
I have always received valuable information in this forum and I hope someone here as seen or used the Siemens resistors before and can tell me what is so special.
Thanks.
