How Net Metering Works – Ephrata vs. Standard Regulations

This is how net metering works in the United States and also in Pennsylvania. Excess generated kilowatts are credited back to the customer on the next months bill. A very simple plan that promotes solar usage.

Ephrata Borough does not have a simple diagram, but their model involves a meter between the solar panels and the house so that they are able to in fact tax the sun. This is how Customer Owned Generation works in the Borough of Perkasie and apparently the Borough of Ephrata as it appears as Ephrata has copied and pasted the rules from Perkasie and forgot to change the web page title on their site.




General The customer shall be in compliance with all applicable land use, zoning,  planning, electric tariff rules and regulations and the applicable tariff classification and  rates. The terms and conditions contained herein are in addition to, but do not modify  nor negate, the terms of the tariff. 

If generation is allowed by the Borough, a net meter and a customer generation meter  shall be provided by the Borough for the installation. Customer shall bear responsibility  for all equipment, metering equipment, wiring and installation in support of Borough  requirements including reimbursement to the Borough of both net meter and customer  generation meter costs. Meter locations shall be as approved by the Borough.  

Each month the net meter and customer generation output meter shall be read by the  Borough. The amount of kWhs to be billed for energy shall be the net amount of energy  equal to the energy provided by the Borough minus energy returned to the Borough from  the customer owned generation source. Billed energy shall not be less than zero in any  month. Excess energy shall be recorded monthly and subject to annual true up as  described below. Monthly distribution charges shall be based upon the sum of the  energy provided by the Borough minus the energy returned to the Borough) plus the  customer generation output in kWh. Monthly demand charges (if applicable) shall be as  recorded by the net meter. All charges shall be determined as provided by ordinance or  resolution of the Borough.  

Installations in service prior to the date of these Technical Requirements shall not be  subject to the requirement of a customer generation meter.  

Annual True-up 

The Borough shall reimburse customers for excess energy received by the Borough from the customer on an annual basis. The customer shall receive payment for the annual excess energy calculated as the sum of each month’s excess energy. The  amount of annual excess energy cannot exceed the amount of annual energy purchased  from the Borough. Reimbursement to the customer shall be at the applicable Base  Power Supply Cost in effect at the time of reimbursement or another established rate at  the mutual agreement of the customer and the Borough. Installations in service prior to  the date of these Technical Requirements that do not have a customer generation meter  shall have applicable distribution charges deducted from any credit due to the customer. 

I Purpose – The purpose of this document (relating to interconnection of on-site  customer generation and parallel generation requirements) is to clearly state the terms  and conditions that govern the interconnection and operation of on-site customer  generation, in order to: 

A. establish technical requirements Which will promote the safe and reliable  parallel operation of customer generation resources; 

B. enhance the reliability of electric service;




C. facilitate the implementation and use of distributed resources  technologies; 

D. enhance economic efficiency in the production and consumption of  electricity and other energy; and 

E. promote the use of distributed resources in order to provide electric  system benefits during periods of capacity constraint. 

II Applicability – Unless otherwise provided, these guidelines apply to all customer  generation interconnected and operated in the Borough of Ephrata power delivery  system. The interconnection and parallel operation of on-site customer generation  operating above 100 kW shall be reviewed on an individual case basis.  

III Definitions 

A. Account – An account is one metered or un-metered rate or service  classification which normally has one electric delivery point of service.  Each account shall have only one electric service supplier providing full  electric supply requirements for that account. A premises may have more  than one account. 

B. Company – Borough of Ephrata (Hereinafter called Borough). 

C. Consumption – Electricity passing through the electric meter from the  Borough’s distribution system to the customer. 

D. Customer – Any adult person, partnership, association, corporation, or  other entity: (i) in Whose name a service account is listed, (ii) Who  occupies or is the ratepayer for a premises, building, structure, etc., and  (iii) Who is primarily responsible for payment of bills. A customer includes  anyone taking Delivery Service or combined Electric Supply & Delivery  Service from the Borough under one service classification for one  account, premises or site. Multiple premises or sites under the same  name are considered multiple Customers. 

E. Customer Generator Meter – Electric Meter measuring how much  electricity has been generated by customer owned and operated  generation, Customer generation meter shall be paid for by customer,  owned and operated by the Borough. 

F. Demand Charge – Charge for the peak load that is drawn by a customer  in any 15 minute period throughout the month as recorded by the  Borough net meter. The measurement of demand is kilowatts (kW). 

G. Distribution Charge – Charge for the use of local wires, transformers,  substations, and other equipment used to deliver electricity to end-use  consumers from the high voltage transmission lines. Each month, the  distribution charge billing determinant shall equal the energy provided by  the Borough minus the energy returned to the Borough plus the customer  generation output in kWh 




H. Distribution System – Parts of the electric power system between the  Borough point of power delivery and the consumers’ service point of  contact including distribution substations; primary distribution feeders;  distribution transformers; secondary circuits, including the services to the  consumer; and appropriate protective and control devices.  

I. Energy Charge – a charge based on the electric energy (kWh)  consumed. Each month, the energy charge billing determinant shall equal  the net amount of energy, consumed by the customer, metered through the net meter. If the amount of energy billed is zero or less there shall be  no energy charge. Additional charges including but not limited to  customer charge, demand charge, PCA, distribution charge and other  charges as adopted by Borough ordinance or resolution shall apply.  

J. On-Site Customer Generation – An electrical generating unit of less than  100 kW, which may be connected to the Borough electric system.  Installations up to and including 100 kW in size shall be allowed. Larger  installations shall be evaluated for approval by the Borough on a case by 

case basis.  

K. Generator Owner – The owner of the generating system that is  interconnected to the Borough electric system. 

L. Grid – The interconnected arrangement of lines and transformers that  make up the Borough electric power system. 

M. IEEE Standard 929 – IEEE Standard entitled Recommended Practice for  Utility Interface of Photovoltaic (PV) Systems, latest approved revision  thereof. 

N. Interconnection – The physical connection of customer generation to the  Borough system in accordance with these guidelines so that parallel  operation can occur. 

O. Interconnection Application – The standard form of application or letter  which must be submitted by the Generation Owner to the Borough for  permission to interconnect with the Borough system.  

P. Inverter – A static power converter with control, protection and filtering  functions that converts Direct Current input to Alternating Current output.  Inverters must be of the non-islanding type. 

Q. Island – A portion of the utility system which contains both load and  distributed generation and is isolated from the remainder of the utility  system. 

R. Net Meter – Electric meter capable of measuring the difference  between the energy supplied by an electric utility and the energy




generated by a customer-generator when any portion of the energy  generated by the alternative energy generating system is used to offset  part or all of the customer-generator’s requirements for electricity. Net  meter shall be paid for by customer, owned and operated by the Borough. 

S. Parallel Operation – Any electrical connection between the Borough system and the Generator Owner’s generating source. 

T. Point of Common Coupling – The point where the electrical conductors  of the Borough system are connected to the Customer’s conductors and  where any transfer of electric power between the Generator Owner and  the Borough electric system takes place. 

U. Pre-Approved Equipment – Specific generating and protective  equipment system or systems that have been approved by the Borough as meeting the applicable parts of this document. 

V. Pre-Interconnection Study – A study or studies which may be  undertaken by the Borough in response to its receipt of a completed  application for parallel operation with the Borough’s system submitted on  the Interconnected Application form prescribed by these guidelines. Pre 

Interconnection Studies may include, but are not limited to service  studies, coordination studies and facilities impact studies. 

W. Qualifying Facility (QF) – An electric generation facility which is a  qualifying facility under Subpart B, Section 201 of the Federal Energy  Regulatory Commission’s regulations per the Public Utility Regulatory  Policies Act of 1978. 

X. Stabilized – The Borough’s system following a disturbance which returns  to the normal range of voltage and frequency for at least 5 minutes or  longer as coordinated with the Borough. The Borough may require a  longer period upon a reasonable showing that the reconnection after 5  minutes will adversely affect the safety and reliability of the electric  system. 

Y. Unit – A distributed generation facility. 

Z. Utility System or Electric Distribution Facility – Borough’s distribution  system operating to which the generation equipment is interconnected. 

IV Interconnection Application – A proposed Generator Owner will make a  formal application to the Borough for the interconnection of a generator to the Borough system. The customer shall submit documentation to the Borough stating the technical  aspects of the installation, two clean copies of equipment catalog cuts and two copies of  a one line diagram of the proposed installation and interconnection to the Borough  system, accompanied by written representation by the customer that the installation will  be constructed and operated in full compliance with the Borough standards and 




requirements shall be included. For inverted installations, a statement that the inverter  for the project is of the non-islanding type to prevent back feeds shall also be included. 

V. Designation of Borough Contact Persons for Matters Relating to  Distributed Generation Interconnection – The Borough Electric Division  Superintendent will be the designated point of contact for all matters related to  interconnected generation. The Borough Electric Division will maintain records  concerning applications received for interconnection and parallel operation of distributed  generation. Such records will include the date of receipt of each such application,  documents generated in the course of processing such applications, correspondence  regarding such applications and the final disposition of such application. 

VI. Pre-Interconnection Studies – The Borough reserves the right to conduct a  service study, coordination study, or facilities impact study prior to approval of a  distributed generation unit. In instances where such studies are deemed necessary, the  scope of such studies shall be based on the characteristics of the particular distributed  generation unit to be interconnected and the proposed point of interconnection. 

A) Completion of Pre-interconnection Study – Upon completion of the  interconnection study, the Borough will notify the Generator Owner that  the application has been approved or indicate in sufficient detail why the  application cannot be approved.  

B) Pre-interconnection Study Fee – The Borough will do a pre interconnection study without charge up to the typical and customary cost  that the Borough would expend for study work of similar type of customer  interconnection. If the cost to the Borough is expected to exceed this  typical and customary amount, or if multiple submittals by the Generator  Owner are necessary, the Borough will advise the Generator Owner of  the expected cost of such study work by the Borough before such work  begins. The Generator Owner will be responsible for payment of all costs  above the typical and customary amount. 

VII Interconnection of Distributed Generation – Where generation is capable of  exporting power to Borough system, the interconnection study may result in more  stringent interconnection requirements. 

VIII Pre-approval of Generation units, Devices and Systems – Upon approval by  the Borough that certain generating unit’s protective devices and/or system(s) meet the  standards set out in these guidelines, such approval shall be made available to the  appropriate manufacturer upon written request. For subsequent applications using some  or all of the identical generating unit’s protective devices and/or systems, the applicant 

may submit a copy of the approval with the application as proof that its equipment has  already been approved for use on the Borough’s system. Use of pre-approved  equipment will not eliminate any applicable requirement for a pre-interconnection study  to determine the suitability of the equipment for each application, given the unique  arrangements and characteristics of both the Generator Owner and Borough systems at  the point of the interconnection.




IX Connection Approval – The Generator Owner can connect their generation to  the Borough system only after the Interconnection Application has been approved and  the Generation Owner has received approval notification.  

X Interconnected Generation Site Warning Label – The Generator Owner will  install a warning label in a conspicuous place on their electric meter or meter box to  notify Borough personnel that there is a generator source installed on the load side of  the meter. The warning label shall not be placed in a location that would interfere with  the ability of Borough personnel to read the electric meter. The warning label must be  placed before the generation can be interconnected. 

XI Disconnection and Reconnection. – The Borough may disconnect a service with a distributed generation unit under the following conditions: 

A. Application Termination – Upon termination of the approved  Interconnection Application  

B. Non Compliance – For non-compliance with the technical guidelines  specified in this document or other requirement contained in the  applicable Customer Tariff, provided that the Borough has given notice to  the Generator Owner and provided the Generator Owner reasonable time  (consistent with the condition) to correct such non-compliance. The  Borough will reconnect the service only upon receipt of certification from  the Generator Owner and verification by the Borough that the unit is in  compliance.  

C. In Case of a system emergency or outage of the Borough Electrical  Sources – The Generator Owner’s generation equipment must be  installed and configured so that parallel operation must automatically  cease immediately and automatically during outages or loss of the  Borough electric source in accordance with these guidelines. The  Generation Owner must also cease parallel operation upon notification by  the Borough of a system emergency, abnormal condition or in cases  where such operation is determined to be unsafe, interferes with the  supply of service to other customers or interferes with the Borough’s  system maintenance or operation. In addition, the Borough may  disconnect the generator from the Borough system for system  emergencies without notice.  

D. For Routine Maintenance and Repairs – The Borough may disconnect  a Customer/Generation Owner for routine maintenance and repairs on  the Borough system.  

The Borough will reconnect the Customer/Generation Owner as quickly  as possible following any such service interruption. 

XII Termination – The Generation Owner may terminate the approved  Interconnection Application upon thirty (30) days written notice to the Borough. 




The Borough may terminate the Interconnection Application for cause. The  Generator Owner must give the Borough notice that it intends to permanently  shut down his generation. 

XIII Privileged Communications Concerning Proposed Distributed Generation  Projects – In the course of processing applications for parallel operation and in  the conduct of pre-interconnection studies, the Generation Owner shall provide  the Borough with detailed information concerning the proposed distributed  generation project and note as privileged, on each applicable sheet and  information considered privileged. If any submitted information is requested by a  third party, notice shall be given by the Borough to the Generator Owner. It shall  be the responsibility of the generation owner to legally challenge the release of  this information. 

XIV Technical Guidelines for Parallel Operation of On-site Distributed  Generation Units – This subsection describes minimum requirements and  procedures for safe and effective connection and operation of distributed  generation. A Generator Owner may operate 60 Hertz, three phase or single  phase generating equipment, Whether a QF or non-QF, in parallel with the  Borough’s system pursuant to an approved Interconnection application provided  that the equipment and Generator Owner meet or exceed the requirements of  these guidelines and that the Borough has approved the Generator Owner’s  application to interconnect. This subsection describes typical interconnection  requirements. Certain specific interconnection locations and conditions may  require the installations of additional protective settings or hardware, especially  when exporting power to the system. If the Borough, in the Borough’s sole  opinion, concludes that an application for parallel operation requires additional  protective settings or hardware, the Borough shall make those requirements  known after all pertinent studies are completed. 

Approval to connect to the Borough system indicates only that the minimum  Borough electrical requirements for a safe proper interconnection have been  satisfied. Such approval does not imply that the Generator Owner’s facility meets  all land use, zoning, planning or federal, state and local standards or regulations. 

A) General Interconnection and Protection Requirements. 

1) The Generator Owner’s generation and interconnection installation must  meet all Borough land use, zoning, planning and applicable national,  state, and local construction and safety codes. 

2) The Generator Owner’s generator shall be equipped with protective  hardware and software designed to prevent the generator from energizing  the Borough’s de-energized circuits. The Generator Owner’s generator  must automatically disconnect from the Borough’s system if the Grid  source is lost, irrespectively of connect loads or other generators. 

3) The generator shall be equipped with the necessary protective hardware  and software designed to prevent sustained parallel operation of the 




generating equipment with the Borough system unless the system service  voltage and frequency are within acceptable magnitudes. 

4) Pre-approved equipment for the project site, approved by the Borough, shall be accepted as part of an interconnection proposal without the need  to re-review the equipment itself. However, the application, design and  setting of pre-approved units and/or equipment must be reviewed and  coordinated according to the unique needs of the specific location of the  proposed installation.  

5) The Generator Owner will be responsible for protecting its own generating  and interconnection equipment in such a manner so that Borough system  outages, short circuits, single phasing conditions or other disturbances  including zero sequence currents and ferroresonant over-voltages do not  damage the Generator Owner’s generating equipment. The protective  equipment shall also prevent excessive or unnecessary tripping that  would adversely affect the Borough’s service reliability to other Generator  Owners and Customers. 

6) The generator and interface protection schemes shall be continuously  monitored and functioning and the generator shall immediately disconnect  from the Borough’s system for any condition that would make the  protection scheme inoperable. 

7) The operating power required for the protection and control schemes for  the generator and the control power used to disconnect the generator  from the Borough must not be dependent on local Borough power. 

8) Where multiple generators are connected to the system through a single  point of common coupling, the sum of the ratings of the generators will be  used to determine the applicability of these guidelines. Protection scheme  performance with one or more units off line will have to be considered. 

9) Applicable circuit breakers or other interrupting devices at the Generator  Owner’s facility must be capable of interrupting the maximum available  fault current at the site, including any contribution from the Owner’s  generator(s). 

10) The Generator Owner will furnish and install a manual disconnect device  Which, When opened, will have the effect of isolating the generator from  the Borough’s system. The disconnect device shall have a visual break (a  disconnect switch, a draw-out breaker, fuse block, etc. as appropriate to  the voltage level), and shall be accessible to the Borough’s personnel,  and shall be capable of being locked in the open position via a Borough  padlock. The Borough shall use reasonable efforts to utilize padlocks of a  size consistent with typical manufacture’s specifications. The Generator  Owner shall follow the Borough’s switching, clearance and tagging  procedures.




11) The design, procurement, installation, and maintenance of the equipment  at the Generator Owner’s site is the responsibility of the Generator Owner  and at the Generator Owner’s expense. Customer shall provide and  install Borough approved meter bases for both Borough Net meter and  Borough customer generation meter. Customer shall reimburse Borough  for cost of customer generation net meter. 

12) Any necessary enhancements or improvements needed within the  Borough’s system and/or at the Customer sites to accommodate the  parallel interconnection of the Generator Owner’s generation will be at the  Generator Owner’s expense. 

13) The Generator Owner has full responsibility and liability for the safe and  proper operation of their equipment and the power originating from their  generator. The Generator Owner is also responsible for synchronizing  their generator(s) with the Borough’s system and maintaining a  synchronous operation. 

14) The Generator Owner must immediately cease parallel operation upon  notification by the Borough if such operation is determined to be unsafe,  interferes with the supply of service to other customers, or interferes with  the Borough’s system maintenance or operation. 

15) The Borough reserves the right to specify the type of transformer  connection (e.g. delta-delta, wye-delta, wye-wye) that will be employed  for all multiphase interface transformers consistent, Where reasonable,  with the Generator Owner’s power system. 

B) Prevention of Generator Owner Generation Interference with the  Borough System. To eliminate undesirable interference caused by  operation of the Generator Owner’s generating equipment, the Generator  Owner’s generator shall meet the following criteria: 

1) Voltage – The generating equipment will be operated in such a manner  that the voltage levels on the Borough’s system are in the same range as if  the generating equipment were not connected to the Borough’s system. The  Generator Owner shall provide an automatic method of initiating a disconnect  sequence of his generating equipment from the Borough system with set  points noted in the table below.




Generating Systems  with Inverters Up to 25 kWGenerating Systems  with Inverters Greater than  25 kWNon-Inverter or  Rotating Machine Generating  Systems
∙ Trip in 0.1 second for  V<50% ∙ Trip in 2 second for  50%≤V<88% ∙ Trip in 2 seconds for  106%<V<137% ∙ Trip in 0.03 second for  137%≤V (Above times and  voltages taken directly from IEEE  929)∙ Trip in 0.1  Second for  V <50% ∙ Trip within 0.1 to  30 seconds for 50%≤V<88% ∙ Trip within 0.1 to 30  seconds for 106%<V<137% ∙ Trip in 0.03 second for  137%≤V (Specific voltage and  time delay set points will  be determined for each  installation.)∙ Trip in 0.1  second for  V≥115% ∙ Trip within 0.1 to  30 seconds for  V>110% or V<90% (Specific voltage and  time delay set points will  be determined for each  installation.)

Note: Trip time refers to the time between when the abnormal voltage condition  occurs and the generator being disconnected from the Borough system. 

On three phase generator installations, full three phase voltage sensing shall be  employed. Voltages must be sensed on the high side of any interface transformer  if the transformer high voltage winding is ungrounded. 

The Generator Owner may reconnect to the grid when the system voltage returns  to normal range and is stabilized as defined in Section III, Definitions. 

2) Flicker – The Generator equipment or operation of equipment shall not  cause voltage flicker on the Borough’s system or to any other Borough customer. This flicker shall not exceed the “Borderline of Irritation” curve,  as defined in IEEE Std 519-1992, Recommended Practices and  Requirements for Harmonic Control in Electric Power Systems. Lower  levels of flicker may be required in areas where equipment such as  computers and instrumentation are impacted. 

3) Frequency – The operating frequency of the generating equipment shall  not deviate more than the values noted in the table below.




Generating Systems  with Inverters Up to 25 kWGenerating Systems with  Inverters Greater than 25 kWNon-Inverter or Rotating Machine Generating  Systems
∙ Trip in 0.1 second for  F<59.3 Hz ∙ Trip in 0.1 second for  F>60.5 Hz. (Set points taken from IEEE 929)∙ Trip in 0.1 second for  F<59.3 Hz ∙ Trip in 0.1 second for  F>60.5 Hz. (Other frequency and time  delay set points may be  necessary for a specific  installation.)∙ Trip in 0.1 second for  F<59.3 Hz ∙ Trip in 0.1 second for  F>60.5 Hz. (Other frequency and time  delay set points may be  necessary for a specific  installation.)

Note: Trip time refers to the time between when the abnormal frequency condition  occurs and the generator being disconnected from Borough. 

The Generator Owner may reconnect when the system frequency returns  to normal range and is stabilized as defined in Section III, Definitions. 

4) Harmonics – Non-linear circuit elements such as inverter can produce  harmonics. Per IEEE Std 519, Recommended Practices and  Requirements for Harmonic Control in Electric Power Systems, the total  harmonic distortion (THD) voltage shall not exceed 5% of the  fundamental 60 Hz frequency nor 3% of the fundamental for any  individual harmonic as measured at the location Where the customer  interfaces with the Borough’s system (Point of Common Coupling). In  addition, the level of harmonic current that the customer is allowed to  inject into the Borough’s system shall not exceed that specified in IEEE  Std 519. Furthermore, any communication notch shall be limited as  defined by IEEE Std 519. The preceding requirements apply to all types  of generation systems. 

The Generator Owner is responsible for the installation of any necessary  controls or hardware to limit the voltage and current harmonics generated  by his equipment to defined levels. 

5) Power Factor – The generator must not adversely impact the power  factor of the Generator Owner site. Inverters shall be designed to operate  close to unity power factor. The operating power factor of the generator  shall be contained within the limits defined in the table below.

Generating Systems  with Inverters Up to  25 kWGenerating Systems with  Inverters Greater than  25 kWNon-Inverter or Rotating Machine Generating  Systems
0.985 Lagging or Leading  When output exceeds  10% of inverter rating.0.985 Lagging or Leading  When output exceeds 10% of inverter rating.0.985 Lagging or Leading




However, to the extent that a Generator Owner’s power factor at the Point  of Common Coupling falls below 0.985 lagging, the Generator Owner  must obtain, install and maintain, at his expense, corrective apparatus  that compensates for the drop in power factor caused by the installation  of the generator. 

6) Current – In some cases, directional over-current protection may be  required to limit fault current flowing onto the Grid in the event of a line  fault. DC inverters that are incapable of producing fault current do not  require directional over-current protection. 

Inverter systems shall not inject DC current greater than 0.5% of rated  inverter output in the AC interface point under either normal or abnormal  conditions. 

7) Fault and Line Clearing – The Generator Owner shall automatically  disconnect from the Borough’s system during electrical faults on the  Borough’s electrical system and upon loss of the Borough’s electric  source. The Generator Owner may reconnect when the system voltage  and frequency return to normal range and is stabilized as defined in  Section III, Definitions. Detection of the loss of the Borough’s primary  electric system, Where the Generator Owner is operating in an island with  other customer load, becomes increasingly difficult as the level of  dispersed generation on a feeder approaches the connected load. For  generating units 25 kW and below, the over/under voltage and over/under  frequency settings described previously along with the anti-islanding  provisions of IEEE 929/UL 1746 inverters, shall be sufficient to satisfy this  provision. For units greater than 25 kW the voltage and frequency set points are to be adjustable, with the actual setting determined by the  Borough based on the electrical characteristics of the generator and the  Borough’s electrical system. In addition, additional protection such as  power directional or directional over current functions may be required.  For units 500 kW or larger, a direct tripping scheme to trip the generator  upon loss of the Borough feeder may be required by the Borough. This  decision will be based on the saturation of distributed generation on a  particular feeder circuit and in those cases where under voltage or under  frequency sensing may not adequately detect loss of the Borough source. 

8) Automatic Reclosing – The Generator Owner is responsible for  protecting his equipment from the effects of switching or automatic  reclosing of the Borough’s feeder circuit.  

C) Control, Protection and Safety Equipment Requirements Specific to Generators of 25 kW1 or less. 

All Generator Owners 10 kW or less can be single phase. Customer owned  generators greater than 10 kW must be evaluated by the Borough to determine if it  can be single phase. The following table describes necessary control, protection and 




safety equipment specific to generator of 25 kW or less connected to Secondary or  Primary Voltage Systems: 

Control, Protection and Safety Equipment for Generators of 25 kW1 or Less  Connected to Secondary or Primary System 

Generator Size 25 kW or less 

Generator Disconnect Device 

Over-Current Trip 

Over-Voltage Trip 

Under Voltage Trip 

Over/Under Frequency Trip 

Synchronizing Check2 Manual or Automatic 


1. Exporting to the Borough system many require additional  operational/protection devices. 

2. For synchronous and other type of generators with stand-alone capability. 

D) Control, Protection and Safety Requirement Specific to Three Phase  Synchronous Generators, Induction Generators, and Inverter Systems. 

Generators greater than 25 kW must be three phase machines connected to three  phase circuits. 

1) Three Phase Synchronous Generators. Generator circuit breakers shall  be three phase devices with electronic or electromechanical control. The  Generation Owner is solely responsible for properly synchronizing his  generator with the Borough’s system. For a synchronous generator, the  excitation system response ratio shall not be less than 0.5 (five-tenth). The  generator’s excitation system(s) shall confirm, as near as reasonably  achievable, to the field voltage vs. time criteria specified in American  National Standards Institute Standard C50.13-1989 in order to permit  adequate field forcing during transient conditions. 

2) Three Phase Induction Generators and Inverter Systems. Induction  generation may be connected and brought up to synchronous speed (as an  induction motor) if it can be demonstrated that the initial voltage drop  measured on the Borough’s side at the point of common coupling is within  the visible flicker limits stated in Section XIV.B.2. Otherwise, the Generator  Owner may be required to install hardware or other techniques to bring  voltage fluctuations to acceptable levels. Line-commutated inverters do not  require synchronizing equipment. Self-commutated inverters whether of the  utility-interactive type or stand-alone type shall be used in parallel with the  Borough system only with synchronizing equipment.




Control, Protection and Safety Equipment1 Less than 1 MW Three Phase  Connected to Primary System 

Generator Disconnect Device2 

Over-Voltage Trip 

Under Voltage Trip 

Over-Current Trip 

Over/Under Frequency Trip 

Ground Over-Voltage Trip3 


Ground Over-Current Trip3 

Synchronizing Check4 Manual or Automatic 

Power Direction5 

Transfer Trip/Reclose Blocking6 


1. Exporting to the Borough’s system may require additional operating/protection  devices and will require coordination of operations with the Borough. 2. For installations of 25 kW or less, the Generation Owner may elect to have the  meter act as the disconnect device with the approval of the Borough.  3. Selection depends on grounding system, if required, by the Borough. 4. For synchronous and other types of generators with stand-alone capability. 5. Required only if generator size is greater than Generator Owner’s minimum load  and thus capable of exporting. The relay will operate if the power flow from the  generator into the Grid exceeds a predetermined level. A time delay will have to  be incorporated into this relay to prevent it from operating during synchronous  swings. 

6. May be required as part of any necessary transfer tripping/reclose blocking  protection scheme. 

E) Requirements Specific to Generators paralleling for 0.1 second or less  (Closed Transition Switching) 

The table below shows the protective functions required by this requirement for  generators less than 1 MW which parallel with the Borough’s system for 0.1 second  or less such as during source or load transfers. 

Control, Protection and Safety Equipment 

Generators Connected to Secondary or primary System Voltage 

For 0.1 Second or Less 

(Closed Transition Switching) 

 Generator Size 

Up to 1 MW 

Over-Voltage Trip 

Under Voltage Trip 

Synchronizing Check1 Manual or Automatic 

Excessive Closed Time Trip2





1. For synchronous and other types of generators with stand-alone capability. 2. Scheme will trip generator if closed transition parallel mode remains in effect  longer than 0.1 second. 

F) Inverter Type – DC Generation installations using inverters for interconnection  with the Borough must use non-islanding type inverters as defined in IEEE 929,  IEEE Recommended Practices for Utility Interface of Photovoltaic (PV) Systems  (including Annex B, D, E & G) and UL Subject 1741, May 1999, Standard for  Static Inverters and Charge Controllers for use in Photovoltaic Power Systems

G) Inspection and Start-Up Testing – the Generator Owner shall provide the  Borough with reasonable prior notice at least 3 weeks before the initial energizing  and start-up testing of the Generator Owner’s generating equipment and the  Borough, at its discretion, shall witness the testing of any equipment and  protective systems associated with the interconnection. The Generator Owner  shall revise and re-submit the application information for any proposed  modification that may affect the safe and reliable operation of the Borough’s system. The generator may be reconnected to the Borough’s system only after  the modified application has been reviewed, testing has been confirmed and the  Borough has given approval to reconnect. 

H) Site Testing and Commissioning – Testing of protection systems shall include  procedures to functionally test all protective elements of the installation up to and  including tripping of the generator and interconnection point. Testing and testing  intervals shall be in accordance with manufacturers’ and industry  recommendations. Testing will verify all protective set points and relay/breaker  trip timing. The Borough may witness the testing of installed switchgear,  protection systems, and generator. The Generator Owner is responsible for all  maintenance of the generator, control and protective equipment. The Generator  Owner will maintain records of such maintenance activities which the Borough may review at reasonable times. For generation systems greater than 500 kW, a  log of generator operations may be required in order to determine its output and  run times for system planning purposes. 

I) Metering – Metering requirements will be reviewed on each specific installation. 

J) Dedicated Transformer – A dedicated transformer will be required Where the  Generator facility is served from the same transformer secondary as another  Borough customer and inverter-based technology not meeting IEEE 929-1999  and IEEE 519-1992 specifications is used. In addition, a dedicated transformer or  other current-limiting device is needed for any type of generator installation  where the increase in available short circuit current could adversely impact other  Borough customers on the same secondary circuit.




K) Suggested References  

The following references can supply technical support and insight into the safe,  reliable interconnection of distributed generation with the Borough electric system.  These references shall be reviewed by those individuals or firms contemplating  parallel operation of generation with the Borough. 

IEEE C37.95-1989 – IEEE Guide for Protective Relaying of Utility-Consumer  Interconnections 

IEEE Std 1001(1988) – IEEE Guide for Interfacing Dispersed Storage and  Generation Facilities with Electric Utility Systems 

IEEE Std 929 – IEEE Recommended Practices for Utility Interface of Photovoltaic  (PV) Systems 

IEEE Std 1021 (1988) – IEEE Recommended Practices for Utility Interconnection of  Small Wind Energy Conversion Systems 

IEEE Std 519 -1992 – IEEE Recommended Practices and Requirements for  Harmonic Control In Electrical Power Systems 

L) Applicable Standards 

All installations, and specifically generation installations, shall meet all requirements,  including but not limited to safety and performance, of the current edition of the National  Electrical Code, applicable Institute of Electrical and Electronic Engineers’ (IEEE) standards (with special reference to IEEE 1547 Standard), Underwriters Laboratories and the  Borough’s specific requirements.




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