How to query for encumbrance amount on an Open status Purchase Order

Summary: We currently have PO139487 that has a status = Open. We are trying to query the tables to identify the encumbrance amount of $ 8,773 (35,700.00 - 26,927.00) using this table - PJC_XCC_BURDEN_DISTS. There should be an encumbrance of $ 8,773. Does anyone happen to know what columns in table PJC_XCC_BURDEN_DISTS would help me identify the encumbrance amount? If there is a better table(s) to help me find the encumbrance amount, please let me know as well.