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what limitations a frequency inverter has if it do not has a precharge circuit?

Created by: Vial at: 8/1/2012 9:27 PM (5 Replies)

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8/1/2012 9:27 PM	Rate (0)
Vial Member Joined: 8/1/2012 Last visit: 9/9/2021 Posts: 9 Rating: (0)	Hello, I would like to know what limitations a frequency inverter has if it do not has a precharge circuit? As I know, it can not be turned on with the DC Bus energized, is it true? Why? What do I have to do for avoid damage if the frequency inverter do not has a precharge? Thank you for attention
	Last edited by: O_Moderator at: 8/2/2012 1:16 PM new subject after splitting from [URL=/tf/WW/en/Posts/34249#top]Precharge resistor for Sinamics S120?</div></div>
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8/2/2012 2:39 PM	Rate (0)
Deleted User Posts: 767 Rating: (69)	Hello Vial, Limitation you are referencing is that with a frequency inverter (i.e. DC-AC power section) is that this type of product is designed to take an input source of power from a dc bus voltage such as for example 620 VDC. Within the frequency inverter, if it does not have an internal precharge circuit then it can not be connected directly to a dc bus voltage source that is already charged to operating voltage(i.e. such as a battery). The reason the frequency inverter can not be directly connected to the dc bus voltage is the capacitorswithin the frequency inverter would be damaged. Therefore, an external precharge circuit must be providedbetween the dc bus supply and the frequency inverter (i.e. DC-AC power section). Attached is an overall one line diagram of recommended precharge circuit from SINAMICS Engineering manual forSINAMICS S120motor modules, which are a DC-AC power section. Deputy Attachment C:\Documents and Settings\summrl\My Documents\FY12\Reference\Forum\MoMo Precharge.pdf (155 Downloads)
Deleted User Posts: 767 Rating: (69)
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8/3/2012 8:43 PM	Rate (0)
Vial Member Joined: 8/1/2012 Last visit: 9/9/2021 Posts: 9 Rating: (0)	Hello, Deputy. Thank you for your answer. Now it is clarified. Do you know whether all Sinamics S120 has precharge circuit internally or it have to be specified to come with precharge Best regards. Vial

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8/3/2012 9:35 PM	Rate (0)
Deleted User Posts: 767 Rating: (69)	Hello Vial, Actually, for SINAMICS S120 loosedrives product none of the DC-AC power sections (called Motor Modules) have internal precharge resistor circuit. This is due to these drives being designed primarily for operation with a dedicated AC-DC power source (called a line module) which has the precharge circuit internally and all motor modules are supplied with dc bus power at same time to build up capacitor voltage at a controlled rate. Therefore, if a DC-AC power section is to be connected to an already dccharged line or a dc battery thenan external precharge circuit must be supplied to protect the motor module. For SINAMICS S120 Cabinet Modules, there is an option L37 which can be ordered from factory which willinclude a precharge circuit to allow themotor module to be connected to an already charged dc bus. Deputy
Deleted User Posts: 767 Rating: (69)
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8/4/2012 8:25 AM	Rate (0)
DavidBrown Gold Member Joined: 6/29/2012 Last visit: 3/16/2023 Posts: 963 Rating: (7)	What resistors do we have to use if we connect a drive module to an already charged dc-bus.

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10/8/2012 9:30 PM	Rate (0)
Vial Member Joined: 8/1/2012 Last visit: 9/9/2021 Posts: 9 Rating: (0)	Hello, Our configurations is:1 - Active Line Module (235KW) and 8 - Motor Module Boosize (4,8 to 46KW) In this case, could the Motor Module turned on with the DC Bus energized (690VDC)? The capacitor is on the Active line or on Motor module? Thanks.

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