<PAGE>
 
                              Exhibit (10)-2
                              Unicom Corporation and Commonwealth Edison Company
                              Form 10-Q File Nos. 1-11375 and 1-1839
                                
                                          


                            Summary Plan Description
                                     of the

                               UNICOM CORPORATION
                                 KEY MANAGEMENT
                                 SEVERANCE PLAN









                                                                   JUNE 15, 1998
<PAGE>
 
                               UNICOM CORPORATION
                         KEY MANAGEMENT SEVERANCE PLAN


1. ESTABLISHMENT AND PURPOSE OF THE PLAN

     The Unicom Corporation Key Management Severance Plan (the "Plan") was
established by Unicom Corporation ("Unicom") to provide certain key employees of
Commonwealth Edison Company ("ComEd") and other subsidiaries of Unicom (jointly
and severally referred to herein as the "Company") certain severance benefits in
the event the employment of such employees terminates under the circumstances
described herein. This document serves as both the Plan document and the summary
plan description which is required to be provided to participants under the
Employee Retirement Income Security Act of 1974 (ERISA).

2. ELIGIBILITY

Each individual who is on the executive payroll of ComEd or on the equivalent
payroll of any other subsidiary of Unicom (an "Executive") shall be eligible for
benefits hereunder in the event such Executive has a Termination of Employment.

3. PARTICIPATION

     Each eligible Executive shall become a participant in the Plan
("Participant") upon his or her execution of an agreement with the Company in
such form as the Company, in its sole discretion, shall require or permit (the
"Severance Agreement"). Each Severance Agreement shall include covenants not to
compete which are substantially in the form attached hereto and made a part
hereof as Exhibit I. As a condition of becoming a Participant hereunder, each
Executive shall also be required to execute, no later than the date of the
Participant's Termination of Employment or, if later, the date which is 45 days
after the date the Executive is provided with a copy of the Plan, a waiver and
release of claims against the Company ("Waiver and Release").

4. BENEFITS

     Benefits under the Plan shall be those described in this Section 4;
provided, however, that if, under the terms of an offer of employment or
employment agreement with the Company made on or before June 1, 1998, a
Participant would be entitled to benefits which exceed the level of benefits
under the Plan, the terms of such offer of employment or other agreement shall
control.

4.1  Severance Pay. Each Participant shall receive severance pay at a monthly
rate equal to 1/12 of the sum of the Participant's annual base salary in effect
as of the date of Termination of Employment (plus Deferred Compensation Units,
if any) plus the Severance Incentive (as defined in Paragraph 6.4). Payment
shall be made biweekly for the duration of the applicable Salary Continuation
Period, as indicated below, commencing no later than the second paydate which
occurs after the date of the Participant's Termination of Employment, but in no
event earlier than the date which is eight days after




<PAGE>
 
the date the Participant returns an executed Waiver and Release to the Plan
Administrator. Payment will be made in accordance with the Company's normal
payroll practices, net of applicable taxes and other deductions.
<TABLE>
<CAPTION>
     Participant Title                    Salary Continuation Period
     -----------------                    --------------------------
     <S>                                  <C>
     Senior Vice President and above               24 months
     Other Officers                                18 months
     Executives (non-officers)                     12 months
</TABLE>

4.2 Incentive Programs. A Participant's Annual Incentive Awards and Long Term
Performance Unit Awards made or payable under the Unicom Corporation Long Term
Incentive Plan (the "LTIP") with respect to the calendar year in which occurs
the Participant's Termination of Employment shall be prorated by multiplying the
amount of such Awards, determined as described below, by a fraction the
numerator of which is the number of days of the Participant's active employment
during such calendar year and the denominator of which is 365. The amount of any
such Awards shall be determined based upon achievement of applicable performance
goals, in accordance with the terms of the applicable incentive program for such
calendar year; provided, however, that a Long Term Performance Unit Award shall
be payable hereunder with respect to any Participant (other than a Participant
who is or who, as of the last day of his or her Salary Continuation Period would
be, eligible to begin receiving retirement benefits under the Commonwealth
Edison Company Service Annuity System (the "Pension Plan")) only if such
Participant was an active employee for at least 24 months of the performance
period with respect to such Award. Payment of Awards under this Section 4.2
shall be made in a lump sum net of applicable taxes and other deductions at such
time as the Awards for such calendar year are payable to active employees.

4.3 Stock Options. No Participant shall be entitled to participate in any grants
of stock options under the LTIP made after such Participant's Termination of
Employment. Except as provided below, any stock options granted to a Participant
prior to such Participant's Termination of Employment shall be exercisable only
to the extent such options are exercisable as of the date of such Termination of
Employment and shall thereafter be exercised in accordance with the provisions
of the LTIP. Stock options which remain unexercisable as of the date of a
Participant's Termination of Employment shall be forfeited. Notwithstanding the
preceding, with respect to any Participant who, as of the date of such
Participant's Termination of Employment (or, if later, the last day of such
Participant's Salary Continuation Period) is eligible to begin receiving
retirement benefits under the Pension Plan, any stock options granted to such
Participant which have not become exercisable prior to the date of the
Termination of Employment shall become fully exercisable on such date, and shall
remain exercisable until the expiration of the option term(s).

4.4 Health Care Coverage. Each Participant shall continue to participate in the
health care plans sponsored by ComEd during the Salary Continuation Period. The
premium for such coverage shall be the premium level in effect for active
employees during such period. Coverage under this Paragraph 4.4 shall be
provided for the duration of the Salary



                                       2
<PAGE>
 
Continuation Period in lieu of continuation coverage under the Consolidated
Omnibus Budget Reconciliation Act of 1985 (COBRA) for the same period. At the
end of the Salary Continuation Period, COBRA continuation coverage may be
elected for the remaining balance of the statutory coverage period, if any;
provided, however that a Participant who has attained at least age 50 (but not
age 55) as of the last day of the Salary Continuation Period and who has
completed (or who, pursuant to the terms of an offer of employment or employment
agreement, is credited with) at least 10 years of service under the terms of the
Pension Plan shall be entitled to elect retiree health coverage under the ComEd
health care plans on the same terms and subject to the same conditions as
individuals who have attained age 55 and are eligible to begin receiving early
retirement benefits under the Pension Plan.

4.5  Retirement Plans. During the Salary Continuation Period, each Participant
shall accrue credited service under the Commonwealth Edison Supplemental
Management Retirement Plan (the "SERP"). The amount of any payment made under
Section 4.1 to the Participant during such period shall be taken into account
for purposes of the SERP, and each Participant may also elect to participate in
the Commonwealth Edison Excess Benefit Savings Plan during the Salary
Continuation Period with respect to the portion of any such payment which is
attributable to base salary. A Participant in the Plan shall not accrue service
or otherwise actively participate in any tax-qualified retirement plan sponsored
by ComEd or the Company during the Salary Continuation Period, and shall not be
entitled to commence to receive benefits under any such plan until after the
expiration of the Salary Continuation Period.

4.6  Life Insurance and Disability Coverage.  Continued coverage under the life
insurance and long term disability plans sponsored by the Company shall be
extended to each Participant through the last day of the Salary Continuation
Period applicable to such Participant on the same terms and subject to the same
conditions as are applicable to active employees.

4.7  Deferred Compensation Plans.  The elections, if any, made by an Executive
under any deferred compensation plan sponsored by the Company shall remain in
effect through the last day of such participant's Salary Continuation Period,
but such individual shall not be entitled to make any additional elections
during such period.

4.8  Executive Perquisites.  Executive perquisites shall terminate effective as
of the date of a Participant's Termination of Employment, and any Company-owned
property shall be required to be returned to the Company no later than such
date; provided, however, that each Participant who is an officer of the Company
shall be entitled to financial counseling services for a period of 24 months
following the date of such Participant's Termination of Employment.

4.9  Outplacement Services.  Each Participant shall be entitled to outplacement
services at the expense of the Company for such period and subject to such terms
and conditions as the Plan Administrator, in its sole discretion, determines are
appropriate.

5.  TERMINATION OF PARTICIPATION; CESSATION OF BENEFITS

                                       3
<PAGE>
 
     A Participant's benefits under the Plan shall terminate on the last day of
the Participant's Salary Continuation Period or, if earlier, on such date as the
Company discovers that the Participant has breached any of the restrictive
covenants contained in the Severance Agreement between the Executive and the
Company which is a condition precedent to the payment of benefits hereunder. In
the event of any such breach, the Company may require the repayment of amounts
paid prior to such breach in accordance with Paragraph 4.1, and shall
discontinue the payment of any additional amounts under Section 4 of the Plan.

6.  DEFINITIONS

     In addition to terms previously defined, when used in the Plan, the
following capitalized terms shall have the following meanings unless the context
clearly indicates otherwise:

6.1  "Cause" means, with respect to any Executive:

     (a) the Executive's willful commission of acts(s) or omissions(s) which
     have, have had, or are likely to have a material adverse effect on the
     business, operations, financial condition or reputation of the Company or
     any of its affiliates;

     (b) the Executive's conviction (including a plea of guilty or nolo
     contendere) of a felony or any crime of fraud, theft, dishonesty or moral
     turpitude; or,

     (c) the Executive's material violation of any statutory or common law duty
     of loyalty to the Company or any of its affiliates.

6.2  "Good Reason" means a material reduction of an Executive's salary,
     incentive compensation or benefits; or a material reduction or material
     adverse alteration in the nature of the Executive's position,
     responsibilities or authority.

6.3  "Salary Continuation Period" means the period indicated in Section 4.1
     during which benefits are payable under the Plan.

6.4. "Severance Incentive" means the average of the Annual Incentive Awards
     paid to a Participant with respect to each of the two calendar years
     preceding the year in which occurs the Participant's Termination of
     Employment.

6.5  "Termination of Employment" means:

     (a)  a termination of the Executive's employment by the Company or any
     subsidiary for reasons other than for Cause as defined below; or

     (b)  a resignation by the Executive for Good Reason.

     A termination of employment for Cause or an Executive's resignation other
     than for Good Reason shall not be a Termination of Employment for purposes
     of the Plan.

                                        4



<PAGE>
 
7. FUNDING

     Nothing in the Plan shall be interpreted as requiring Unicom to set aside
any of its assets for the purpose of funding its obligations under the Plan. No
person entitled to benefits under the Plan shall have any right, title or claim
in or to any specific assets of Unicom, but shall have the right only as a
general creditor of Unicom to receive benefits from Unicom on the terms and
conditions provided in the Plan.

8. ADMINISTRATION OF THE PLAN

     The Plan shall be administered by the Director of Compensation Planning of
ComEd (the "Plan Administrator"). The Plan Administrator may delegate any
administrative duties, including, without limitation, duties with respect to the
processing, review, investigation, approval and payment of severance pay and
provision of severance benefits, to designated individuals or committees. Unicom
shall be a "named fiduciary" under the Plan for purposes of ERISA.

     The Plan Administrator shall promulgate any rules and regulations necessary
to carry out the purposes of the Plan or to interpret the terms and conditions
of the Plan; provided, however, that no rule, regulation or interpretation shall
be contrary to the provisions of the Plan. The rules, regulations and
interpretations made by the Plan Administrator shall be applied on a uniform
basis and shall be final and binding on any Executive or former Executive of the
Company or any successor in interest of either.

9. CLAIMS PROCEDURE

     The Plan Administrator shall determine the rights of any Executive or
former Executive of the Company to any severance pay or benefits hereunder. The
Plan Administrator has the sole and absolute power and authority to interpret
and apply the provisions of this Plan to a particular circumstance, make all
factual and legal determinations, construe uncertain or disputed terms and make
eligibility and benefit determinations in such manner and to such extent as the
Plan Administrator in his or her sole discretion may determine. Any Executive or
former Executive of the Company who believes that he or she is entitled to
receive severance pay or benefits under the Plan, including severance pay or
benefits other than those initially determined by the Plan Administrator, may
file a claim in writing with the Plan Administrator. No later than 90 days after
the receipt of the claim the Plan Administrator shall either allow or deny the
claim in writing.

     A denial of a claim, in whole or in part, shall be written in a manner
calculated to be understood by the claimant and shall include the specific
reason or reasons for the denial; specific reference to pertinent Plan
provisions on which the denial is based; a description of any additional
material or information necessary for the claimant to perfect the claim and an
explanation of why such material or information is necessary; and an explanation
of the claims review procedure.


                                       5
<PAGE>
 
     A claimant whose claim is denied (or his or her duly authorized
representative), may, within 60 days after receipt of the denial of his or her
claim, request a review upon written application to an officer designated by
Unicom and specified in the claim denial; review pertinent documents; and submit
issues and comments in writing.

     The designated officer shall notify the claimant of his or her decision on
review within 60 days after receipt of a request for review unless special
circumstances require an extension of time for processing, in which case a
decision shall be rendered as soon as possible, but not later than 120 days
after receipt of a request for review. Notice of the decision on review shall be
in writing. The officer's decision on review shall be final and binding on any
claimant or any successor in interest.

10. AMENDMENT OR TERMINATION OF PLAN

     Notwithstanding anything in the Plan to the contrary, Unicom's Senior Vice
President of Corporate Resources or another designated officer of the Company
may amend, modify or terminate the Plan at any time by written instrument;
provided, however, that no amendment, modification or termination shall deprive
any Participant of any payment or benefit that the Plan Administrator previously
has determined is payable under the Plan.

11. MISCELLANEOUS

11.1 Limitation on Rights. Participation in the Plan is limited to the
individuals described in Section 3, and the Plan shall not apply to any previous
or subsequent workforce reductions implemented by the Company or to any other
voluntary or involuntary terminations of employment.

11.2 Headings. Headings of sections in this document are for convenience only,
and do not constitute any part of the Plan.

11.3 Severability. If any provision of this Plan or the rules and regulations
made pursuant to the Plan are held to be invalid or illegal for any reason, such
illegality or invalidity shall not affect the remaining portions of this Plan.

11.4 Governing Law. The Plan shall be construed and enforced in accordance with
ERISA and the laws of the State of Illinois to the extent such laws are not
preempted by ERISA.

11.5 Successors and Assigns.  This Plan shall be binding upon and inure to the
benefit of Unicom and its successors and assigns and shall be binding upon and
inure to the benefit of a Participant and his or her legal representatives,
heirs and assigns. No rights, obligations or liabilities of a Participant
hereunder shall be assignable without the prior written consent of Unicom. In
the event of the death of a Participant after he or she has signed the Waiver
and Release, but prior to receipt of severance pay or benefits to which 


                                       6
<PAGE>
 
he or she is entitled hereunder, the severance pay described in Paragraph 4.1
shall be paid to his or her estate, and the Participant's dependents who are
covered under the ComEd health care plans shall be entitled to continued rights
under Paragraph 4.4; provided that the estate or other successor of the
Participant has not revoked such Waiver and Release.

12. ADMINISTRATIVE INFORMATION


Plan Sponsor:                                Unicom Corporation
Address :                                    227 West Monroe Street, 12th Floor
                                             Chicago, Illinois 60606

Employer Identification
Number:                                      36-3961038


Plan Administrator:                          Director, Compensation Planning
Address and Telephone:                       Commonwealth Edison Company
                                             PO Box 767
                                             Chicago, Illinois 60690-0767
                                             (312) 394-4015

Agent for Service of
Legal Process:                               Director, Compensation Planning
                                             Commonwealth Edison Company
                                             PO Box 767
                                             Chicago, Illinois 60690-0767


Plan Number:                                           501

Type of Plan:                                severance benefit plan (welfare)

Plan Year:                                   calendar year

13. ERISA RIGHTS

          As a Participant in the Plan, you are entitled to certain rights and
protections under ERISA. ERISA provides that all plan participants shall be
entitled to:

     Examine, without charge, at the Plan Administrator's office at 10 S.
     Dearborn Street, Chicago, Illinois 60603 all Plan documents and copies of
     all documents filed by the Plan with the U.S. Department of Labor; and

     Obtain copies of all Plan documents and other Plan information upon written
     request to the Plan Administrator. The Plan Administrator may make a
     reasonable charge for the copies.


          In addition to creating rights for Participants, ERISA imposes duties
upon the
                                       7
<PAGE>

people who are responsible for the operation of the Plan. The people who operate
the Plan, called "fiduciaries" of the Plan, have a duty to act prudently and in
the interest of you and other Participants and beneficiaries. No one, including
your employer, your union, or any other person, may fire you or otherwise
discriminate against you in any way to prevent you from obtaining your interest
in the Plan or from exercising your rights under ERISA. If your claim for a
benefit from the Plan is denied in whole or in part, you must receive a written
explanation of the reason for the denial. You have the right to have your claim
reviewed and reconsidered. Under ERISA, there are steps you can take to enforce
the above rights. For instance, if you request materials from the Plan and do
not receive them within 30 days, you may file suit in a federal court. In such a
case, the court may require the Plan Administrator to provide the materials and
pay you up to $110 a day until you receive the materials, unless the materials
were not sent because of reasons beyond the control of the Plan Administrator.
If you have a claim for benefits which is denied or ignored, in whole or in
part, you may file suit in a state or federal court. If it should happen that
Plan fiduciaries misuse the Plan's money, or if you are discriminated against
for asserting your rights, you may seek assistance from the U.S. Department of
Labor, or you may file suit in a federal court. The court will decide who should
pay court costs and legal fees. If you are successful, the court may order the
person you have sued to pay these costs and fees. If you lose and the court
finds your claim to be frivolous, the court may order you to pay these costs and
fees. If you have any questions about the Plan, you should contact the Plan
Administrator. If you have any questions about this statement or about your
rights under ERISA, you should contact the nearest Area Office of the U.S. 
Labor- Management Services Administration, Department of Labor.

June 15, 1998

                                       8
<PAGE>
 
                                   EXHIBIT I
                                   
                           NON-COMPETITION COVENANTS
                           
                                        
1. Confidential Information Defined. For the purposes hereof, the term
   "Confidential Information" shall mean any information not generally known in
   the relevant trade or industry, which was obtained from Unicom Corporation,
   Commonwealth Edison Company or any affiliate thereof (the "Company"), or
   which was learned, discovered, developed, conceived, originated or prepared
   during or as result of your performance of any services on behalf of the
   Company and which falls within the following general categories:

     (a)       information relating to trade secrets of the Company or any
          customer or supplier of the Company;

     (b)       information relating to existing or contemplated products,
          services, technology, designs, processes, formulae, algorithms,
          research or product developments of the Company or any customer or
          supplier of the Company;

     (c)       information relating to business plans or strategies, sales or
          marketing methods, methods of doing business, customer lists, customer
          usages and/or requirements, supplier information of the Company or any
          customer or supplier of the Company;

     (d)       information subject to protection under the Uniform Trade Secrets
          Act, as adopted by the State of Illinois, or to any comparable
          protection afforded by applicable laws; and

     (e)       any other confidential information which either the Company or
          any customer or supplier of the Company may reasonably have the right
          to protect by patent, copyright or by keeping it secret and
          confidential.

2. Nondisclosure of Confidential Information. You agree that you will not use
for your own benefit, in any manner, or disclose any Confidential Information
obtained during your employment with the Company at any time, to any other
person, firm or corporation without the Company's prior written consent, except
as may be required by the lawful order of a court or agency of competent
jurisdiction. You agree to take all reasonable steps to safeguard such
Confidential Information and to protect such information against disclosure,
misuse, loss and theft. Your obligations under this paragraph with respect to
any specific Confidential Information shall cease when that specific portion of
Confidential Information becomes publicly known.
<PAGE>
 
                                                                       Exhibit I


3. Non-Competition.

     (a)       You agree that for a period of two years beginning on the date of
          termination of employment, without the prior written approval of the
          Company you will not, directly or indirectly, in any capacity, engage
          or participate in, become employed by, serve as a director of, or
          render advisory or consulting or other services in connection with,
          any Competitive Business (as defined below).

     (b)       You agree that for a period of two years beginning on the date of
          termination of employment, without the prior written consent of the
          Company, you will not at any time make any financial investment,
          whether in the form of equity or debt, or own any interest, directly
          or indirectly, in any Competitive Business. Nothing in this subsection
          shall, however, restrict you from making an investment in any
          Competitive Business if such investment does not represent more than
          1% of market value of the outstanding capital stock or debt (as
          applicable) of such Competitive Business.

     "Competitive Business" means, as of any date, any individual or entity (and
     any branch, office or operation thereof) which engages in, or proposes to
     engage in (i) the production, transmission, distribution, marketing or sale
     of electricity or (ii) any other business engaged in by the Company prior
     to the separation date which represents for any calendar year or is
     projected by the Company (as reflected in a business plan adopted by the
     Company before the separation date) to yield during any year during the
     first three-fiscal year period commencing on or after the separation date,
     more than 5% of the gross revenue of the Company, and which is located (i)
     anywhere in the United States, or (ii) anywhere outside of the United
     States where the Company is then engaged in, or proposes to engage in, any
     of such activities.

4. Non-Solicitation. You agree that for a period of two years beginning on the
   date of termination of employment, you will not, directly or indirectly:

     (a)       encourage any employee to terminate his or her employment;

     (b)       employ, engage as a consultant or adviser, or solicit the
               employment or engagement as a consultant or adviser of, any
               employee or cause any individual or entity to do any of the
               foregoing;

     (c)       establish a business with, or encourage others to establish a
               business with, any employee; or

                                       2
<PAGE>

                                                                       Exhibit I
 
     (d)            interfere with the relationship of the Company with, or
               endeavor to entice away from the Company any individual or entity
               who or which at any time during the period commencing one year
               prior to the date of termination of employment was a material
               customer or material supplier of, or maintained a material
               business relationship with, the Company.

5. Reasonableness of Restrictive Covenants.

     You acknowledge that the covenants contained in Sections 2, 3 and 4 are
     reasonable in the scope of the activities restricted, the geographic area
     covered by the restrictions, and the duration of the restrictions, and that
     such covenants are reasonably necessary to protect the Company's legitimate
     interests in its Confidential Information and in its relationships with
     employees, customers and suppliers. You further acknowledge such covenants
     are essential elements of this [A]greement and that, but for such
     covenants, the Company would not have entered into this [A]greement. You
     further acknowledge that you have consulted with legal counsel and have
     been advised concerning the reasonableness and propriety of such covenants.
     You acknowledge that your observance of the covenants contained in Sections
     2, 3 and 4 will not deprive you of the ability to earn a livelihood or to
     support your dependents.

6. Right to Injunction; Survival of Undertakings.

     (a)       In recognition of the confidential nature of the Confidential
          Information, and in recognition of the necessity of the limited
          restrictions imposed by Sections 2, 3 and 4 the parties agree that it
          would be impossible to measure solely in money the damages which the
          Company would suffer you were to breach any of your obligations under
          such paragraphs. You acknowledge that any breach of any provision of
          such paragraphs would irreparably injure the Company. Accordingly, you
          agree that if you breach any of the provisions of such paragraphs, the
          Company shall be entitled, in addition to any other remedies to which
          the Company may be entitled under this letter agreement or otherwise,
          to an injunction to be issued by a court of competent jurisdiction, to
          restrain any breach, or threatened breach, of such provisions, and you
          hereby waive any right to assert any claim or defense that the Company
          has an adequate remedy at law for any such breach.

     (b)       If a court determines that any of the covenants included in
          Sections 2, 3 and 4 is unenforceable in whole or in part because of
          such covenant's duration or geographical or other scope, such court
          shall have the power to reduce the duration or scope of such
          provision, as the case may be, so as to cause such covenant to be
          thereafter enforceable.

                                       3