Exhibit 3(a)1

                              AMENDED AND RESTATED
                            ARTICLES OF INCORPORATION
                                       OF
                       PUBLIC SERVICE COMPANY OF COLORADO


      Public  Service  Company  of  Colorado,   a  Colorado   corporation   (the
"Corporation"), pursuant to sections 7-110-106 and 107 of the Colorado  Business
Corporation  Act (the "Act"),  hereby adopts the following  amended and restated
Articles of Incorporation:

     1.   Name.  The name of the  Corporation  is:  Public  Service  Company  of
Colorado

     2.   Purpose.  The  nature,  objects  and  purposes  of the  business to be
transacted  by the  Corporation  shall  be to  engage  in  any  lawful activity
for which corporations may be organized under the Act. The Corporation shall 
have and may exercise all of the rights, powers and privileges  now or hereafter
exercisable by corporations organized under the laws of Colorado.  In  addition,
the Corporation may do everything necessary, suitable, convenient or proper  for
the accomplishment of any of its corporate purposes.

      3.  Stock.  The  total  number  of  shares  of  capital  stock  which  the
Corporation  is  authorized  to issue is ten million  one hundred  (10,000,100),
consisting  of one hundred  (100) shares of common  stock,  one cent ($0.01) par
value  per  share  ("Common  Stock"),  and ten  million  (10,000,000)  shares of
preferred stock, one cent ($0.01) par value per share ("Preferred Stock").

            1.  Preferred  Stock.  The Board of Directors of the  Corporation is
      expressly granted the authority,  by one or more appropriate  filings with
      the  Colorado  Secretary  of  State  pursuant  to the Act,  to  issue  the
      Preferred  Stock in one or more  classes or series,  and to fix, by one or
      more   resolutions   from  time  to  time,  the  number  of  shares,   the
      designations,  powers,  preferences  and rights,  and the  qualifications,
      limitations and restrictions,  of such classes and series of the Preferred
      Stock.  Each share of Preferred Stock of any one series shall be identical
      to each other share of that series,  except as to the dates from and after
      which dividends thereon shall cumulate (if cumulative).

            2. Common Stock. The holders of Common Stock shall have the right to
      vote for the election of directors and on all other matters submitted to a
      vote of the shareholders generally,  with each share entitled to one vote.
      Each share of Common  Stock  shall be equal to every other share of Common
      Stock for all purposes.  Subject to the prior rights and privileges of the
      holders  of  Preferred  Stock (if any),  upon the  voluntary liquidation, 
      dissolution or winding up of the Corporation,  the net assets of the
      Corporation  shall be  distributed  pro rata to the  holders of the Common
      Stock.

      4.  Partial  Liquidation.  The  Board of  Directors  may from time to time
distribute to the shareholders in partial liquidation,  out of stated capital or
capital  surplus  of the  Corporation,  a  portion  of its  assets,  in  cash or
property,  subject to the  limitations  contained  in the  statutes of Colorado.
Shareholders shall share in such distributions in accordance with the provisions
of Article 3 above.

      5. Election of Directors;  No  Cumulative  Voting.  The Board of Directors
shall  consist of one or more  members,  with the number  specified  or fixed in
accordance with the Bylaws of the Corporation. Members of the Board of Directors
may be elected either by written ballot or by voice vote.  The  shareholders  of
the  Corporation  shall not have  cumulative  voting  rights in the  election of
directors or with respect to any other matter.

      6. Indemnification. The Corporation shall indemnify, to the maximum extent
permitted by law, any person who is or was a director, officer, agent, fiduciary
or employee of the Corporation  against any



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claim,  liability  or expense  arising  against or  incurred by such person as a
result of actions  reasonably  taken by him at the direction of the Corporation.
The  Corporation  further  shall  have  the  authority,  to the  maximum  extent
permitted by law and its Bylaws, to indemnify its directors,  officers,  agents,
fiduciaries  and  employees  against  any claim,  liability  or expense  arising
against or incurred by them in all other circumstances and to maintain insurance
at the  Corporation's  expense  providing  for such  indemnification  (including
insurance  with  respect  to  claims,  liabilities  and  expenses  for which the
Corporation does not have the power to indemnify such persons).

      7. Limitation on Director's Liability. A director of the Corporation shall
not be personally  liable to the  Corporation or its  shareholders  for monetary
damages for breach of fiduciary duty as a director, except for liability (i) for
any  breach of the  director's  duty of  loyalty  to the  Corporation  or to its
shareholders,  (ii) for acts or  omissions  not in good  faith or which  involve
intentional  misconduct  or a knowing  violation  of law,  (iii) for a breach of
Colorado Revised Statutes sections.7-108-403,  or (iv) for any transaction from
which the director directly or indirectly derived an improper personal benefit.

      8.  Conflicting  Interest   Transactions.   As  used  in  this  paragraph,
"conflicting  interest  transaction"  means any of the following:  (i) a loan or
other  assistance by the  Corporation to a director of the  Corporation or to an
entity in which a director of the  Corporation is a director or officer or has a
financial  interest;  (ii) a guaranty by the  Corporation  of an obligation of a
director of the Corporation or of an obligation of an entity in which a director
of the  Corporation  is a director  or officer or has a financial  interest;  or
(iii) a contract or transaction  between the  Corporation  and a director of the
Corporation or between the  Corporation and an entity in which a director of the
Corporation is a director or officer or has a financial interest. No conflicting
interest  transaction shall be void or voidable,  be enjoined,  be set aside, or
give  rise to an award  of  damages  or other  sanctions  in a  proceeding  by a
shareholder  or by or in  the  right  of the  Corporation,  solely  because  the
conflicting  interest  transaction  involves a director of the Corporation or an
entity in which a director of the  Corporation is a director or officer or has a
financial interest, or solely because the director is present at or participates
in the meeting of the  Corporation's  Board of Directors or of the  committee of
the Board of  Directors  which  authorizes,  approves or ratifies a  conflicting
interest transaction,  or solely because the director's vote is counted for such
purpose,  if:  (A) the  material  facts  as to the  director's  relationship  or
interest and as to the  conflicting  interest  transaction  are disclosed or are
known to the Board of Directors or the committee,  and the Board of Directors or
committee  in good  faith  authorizes,  approves  or  ratifies  the  conflicting
interest  transaction by the affirmative vote of a majority of the disinterested
directors,  even though the  disinterested  directors are less than a quorum; or
(B) the material facts as to the director's  relationship  or interest and as to
the  conflicting  interest  transaction  are  disclosed  or  are  known  to  the
shareholders  entitled to vote thereon, and the conflicting interest transaction
is specifically authorized,  approved or ratified in good faith by a vote of the
shareholders;  or (C) a  conflicting  interest  transaction  is  fair  as to the
Corporation of the time it is  authorized,  approved or ratified by the Board of
Directors,  a  committee  thereof,  or the  shareholders.  Common or  interested
directors may be counted in determining the presence of a quorum at a meeting of
the Board of Directors or of a committee which authorizes,  approves or ratifies
the conflicting interest transaction.

      9. Loans and Guaranties for the Benefit of Directors. Neither the Board of
Directors nor any committee thereof shall authorize a loan by the Corporation to
a  director  of the  Corporation  or to an  entity  in which a  director  of the
Corporation is a director or officer or has a financial interest,  or a guaranty
by the  Corporation  of an obligation of a director of the  Corporation or of an
obligation of an entity in which a director of the  Corporation is a director or
officer  or has a  financial  interest,  until at least ten days  after  written
notice of the proposed  authorization  of the loan or guaranty has been given to
the  shareholders who would be entitled to vote thereon if the issue of the loan
or guaranty were submitted to a vote of the  shareholders.  The  requirements of
this Article 9 are in addition to, and not in  substitution  for, the provisions
of Article 8 above.

      10. Negation of Equitable  Interests in Shares or Rights.  Unless a person
is recognized as a shareholder through procedures established by the Corporation
pursuant to Colorado Revised Statute sections 7-107-204 or any similar law,  the
Corporation  shall be entitled to treat the  registered  holder of any shares of
the  Corporation  as the owner  thereof for all  purposes  permitted by the Act,
including  without  limitation  all rights  deriving  from such shares,  and the
Corporation  shall not be bound to recognize any equitable or

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other claim to, or interest in, such shares or rights  deriving from such shares
on the part of any other  person,  including  without  limitation,  a purchaser,
assignee  or  pledgee of such  shares or of rights  deriving  from such  shares,
unless and until such purchaser,  assignee,  pledgee or other person becomes the
registered  holder of such shares or is recognized  as such,  whether or not the
Corporation  shall have either actual or constructive  notice of the interest of
such purchaser,  assignee, pledgee or other person. By way of example and not of
limitation,  no such  purchaser,  assignee,  pledgee  or other  person  shall be
entitled  to receive  notice of any  meetings of  shareholders,  to vote at such
meetings, to examine a list of shareholders,  to be paid dividends or other sums
payable to shareholders, or to own, enjoy and exercise any other rights deriving
from such shares,  until such purchaser,  assignee,  pledgee or other person has
become the registered holder of such shares or is recognized as such.

      11.  Registered  Office;  Registered  Agent.  The  street  address  of the
registered office of the Corporation is 1225 17th Street, 9th Floor,  Denver, CO
80202. The name of the registered agent at such address is Paul J. Bonavia.

      12.  Principal  Office.  The  address  of  the  principal  office  of  the
Corporation is 1225 17th Street, Denver, CO 80202.

      These  Amended and  Restated  Articles of  Incorporation  were  adopted by
unanimous  written  consent of the directors of the  Corporation  and by written
consent of the sole shareholder of the Corporation. The number of votes cast for
each amendment by each voting group entitled to vote separately on the amendment
was sufficient for approval by that voting group.

      IN WITNESS WHEREOF, the Corporation has set its hand and seal effective as
of July 10, 1998.

                                 PUBLIC SERVICE COMPANY OF COLORADO



                                 By:     /s/ Wayne H. Brunetti
                                        --------------------------------------
                                      Wayne H. Brunetti, Chief Executive Officer
Attest:



-----------------------------
Cathy J. Hart, Corporate Secretary


                           *     *     *     *     *


      Paul J. Bonavia hereby consents to his appointment as the registered agent
for Public Service Company of Colorado.


                                   /s/ Paul J. Bonavia
                                 ---------------------------------  
                                 Paul J. Bonavia


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