How do fluctuations in Net Working Capital affect Net Debt?

"The company owner has, as part of the on-going operations, a certain capital tied-up in outstanding accounts and inventory as well as a certain financing from suppliers. These balance sheet items (outstanding accounts + inventory - supplier debt) constitute the core of the net working capital, which, however, is sometimes defined as (i) current assets with the exception of liquid funds deducted by (ii) short-term obligations which do not form part of the net debt. Fluctuations in these items, which have a direct effect on the net debt often occur during normal operations."