why VSM for SLM

Hello,

as SLM has no closed loop control, the VSM10 has less influence, but it would be necessary for example, if you have a main switch in front of the infeed without leading auxiliary contact.

 Hello Ziemens,

Ziemens

 1. It means that if the main switch is to be turned off, the VSM will inform the SLM, so it will shut down before the power is cut?

2. Why the small size SLM (5&10kw) do not require a VSM as per catalogs?

1.  yes, but of course not before the power is cut - immediately when the power is cut the regenerative operation is disabled
2. these modules have no Drive-CLiQ, so their control is internal and not within the CU, for these modules the leading contact is mandatory,

Hello Ziemens,

the leading contact has nothing to do with filters or reactors of the SLM.
The leading contact is required to disable the infeed early in case of opening the main switch.

Hello Ziemens,

the VSM10 is intended for the use with an infeed ALM or SLM.
So you can`t use it for this purpose without an infeed, which is linked to the VSM10.

The VSM10 is reacting quick enough on a power loss so you don`t need a leading contact.
Without it you will get drive or infeed errors, because the drives are disabled due to the loss of supply voltage.
With a leading contact the drives are disabled and stopped in a controlled manner beforehand.