Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2017

The table below contains significant affiliate transactions among the companies and related parties including billings under the Interchange Agreement for the years ended Dec. 31:



(Thousands of Dollars)	2017		2016		2015
Operating revenues:
Electric	$	177,234	$	170,483	$	163,255
Operating expenses:
Purchased power	421,609		413,615		419,028
Transmission expense	68,613		61,920		54,070
Natural gas purchased for resale	47		41		45
Other operating expenses — paid to Xcel Energy Services Inc.	92,715		106,454		93,890
Interest expense	7		4		2

Accounts receivable and payable with affiliates at Dec. 31 were:



	2017				2016
(Thousands of Dollars)	Accounts Receivable		Accounts Payable		Accounts Receivable		Accounts Payable
NSP-Minnesota	$	—	$	17,825	$	—	$	18,567
PSCo	—		61		—		974
SPS	—		7		333		—
Other subsidiaries of Xcel Energy Inc.	3,391		11,735		—		9,496
	$	3,391	$	29,628	$	333	$	29,037