1.      Manual Disconnect 

A manual load break disconnect switch that provides clear indication of the switch position and is appropriate to the voltage level shall be available at the customer's main service point to provide a separation point between the customer's electrical generation system and Bryan Texas Utilities’ (BTU) electrical system.  BTU will coordinate and approve the location of the disconnect switch.  The disconnect switch shall be easily visible, mounted separately from the metering or inverter equipment, readily accessible to BTU personnel at all times, and capable of being locked in the open position with a BTU padlock.  Bryan Texas Utilities reserves the right to open the disconnect switch isolating the customer's electrical generating system (which may or may not include the customer's load) from BTU’s electrical system for the following reasons:

a.       To facilitate maintenance or repair of BTU’s electrical system;

b.      When emergency conditions exist on BTU’s electrical system;

c.       When the customer's electrical generating system is determined to be operating in a hazardous or unsafe manner or unduly affecting BTU’s voltage waveform;

d.      When the customer's electrical generating system is determined to be adversely affecting other electric consumers on the BTU system;

e.       Failure of the customer to comply with applicable codes, regulations and standards in effect at that time;

f.       Failure to abide by any contractual arrangement or operating agreement with Bryan Texas Utilities.

2.      Voltage 

BTU shall endeavor to maintain the distribution voltages on the electrical system but shall not be responsible for factors or circumstances beyond its control. The customer shall provide an automatic method of disconnecting generation equipment from BTU’s electrical system within 10 cycles should a voltage deviation greater than +5% or -10% from nominal be sustained for more than 30 seconds (1800 cycles) or a voltage deviation greater than +10% or -30% from nominal be sustained for more than 10 cycles.  If high or low voltage complaints or flicker complaints result from the operation of the customer's electrical generation, the customer's generating system shall be disconnected until the problem is resolved.

3.      Frequency 

BTU shall endeavor to maintain a 60-hertz nominal frequency on the electrical system. The customer shall provide an automatic method of disconnecting generation equipment from BTU’s electrical system within 15 cycles should a deviation in frequency of +0.5Hz or -0.7Hz from nominal occur.

4.      Harmonics 

In accordance with IEEE 519, the total harmonic distortion (THD) of voltage shall not exceed 5% of a pure sine wave of 60-hertz frequency or 3% of the 60-hertz frequency for any individual harmonic when measured at the point of interconnection with BTU’s electrical system. Also, the total current distortion shall not exceed 5% of the fundamental frequency sine wave. If harmonics beyond the allowable range result from the operation of the customer's electrical generation, the customer's generating system shall be disconnected until the problem is resolved.

5.      Flicker           

The distributed generation facility shall not cause excessive voltage flicker on BTU’s electrical system. This flicker shall not exceed 3% voltage dip, in accordance with IEEE 519 (Section 10.5), as measured at the point of interconnection.

6.      Power Factor 

The customer's electrical generation system shall be designed, operated and controlled at all times to provide reactive power requirements at the point of interconnection from 0.95 lagging to 0.95 leading power factor.  Induction generators shall have static capacitors that provide at least 95% of the magnetizing current requirements of the induction generator field.  BTU may, in the interest of safety, authorize the omission of capacitors.  However, where capacitors are used for power factor correction, additional protective devices may be required to guard against self-excitation of the customer's generator field.

7.      Loss of Source 

The customer shall provide UL approved protective equipment necessary to immediately, completely and automatically disconnect the customer’s electrical generation equipment from BTU’s electrical system in the event of a fault on the customer's system, a fault on BTU’s system or loss of source on BTU’s system.  Such protective equipment shall conform to the criteria specified in UL 1741. The customer’s generating system shall automatically disconnect from the grid within 10 cycles if the voltage on one or more phases falls and stays below 70% of nominal voltage for at least 10 cycles. The automatic disconnecting device may be of the manual or automatic reclose type and shall not be capable of reclosing until after BTU’s service voltage and frequency are restored to within the normal operating range and the system is stabilized. 

8.      Coordination and synchronization 

The customer shall be solely responsible for coordination and synchronization of the customer's electrical generating system with all aspects of BTU’s electrical system, and the customer assumes all responsibility for damage or loss that may occur from improper coordination and synchronization of its generating system with BTU’s electrical system. 

9.      Metering 

The actual metering equipment required, its voltage rating, number of phases and wires, size, current transformers, number of input and associated memory is dependent upon the type, size and location of the electric service provided.  In situations where power may flow both in and out of the customer's electrical system, power flowing into the customer's electrical system will be measured separately from power flowing out of the customer's electrical system.  BTU will provide, subject to existing rate schedules at the time of application, the metering equipment necessary to measure capacity and energy delivered to and from the customer.   This includes a separate PV meter for the purpose of measuring the total system output.   

10.  Interconnection Study 

If BTU determines that an interconnection study is necessary, BTU shall perform (or have performed by an outside engineering firm) the study under terms and conditions agreed upon by both the customer and BTU and at the customer's sole expense.  No interconnection study shall be necessary and no study fee will be charged if all of the following apply:

a.       The proposed generation equipment is pre-certified

                                                              i.      Generation equipment with capacity less than 100 kW AC shall be considered pre-certified if a UL 1741 listed inverter is used as well as UL 1703 listed PV modules;

b.      The proposed generation system does not export more than 15% of total load on the feeder serving the proposed facility; and

c.       The proposed generation system does not contribute more than 25% of the maximum possible short circuit current of the feeder serving the proposed facility.

11.  Protection requirements

The distributed generation facility must have an interconnection disconnect device and a generator disconnect device, both capable of interrupting the maximum available fault current supplied by the generator and BTU; an over-voltage trip; an under-voltage trip; an over/under frequency trip; and a manual or automatic synchronizing check (for facilities with stand-alone capability). Facilities rated over 10kW, three phase, must also have reverse power sensing and either a ground over-voltage or a ground over-current trip depending on the grounding system. Grounding shall be done in accordance with UL 1741 and NEC Article 250.

12.  Additional requirements for three-phase generators

a.      Synchronous machines

                                                              i.      The distributed generation facility’s circuit breakers shall be three-phase devices with electronic or electromechanical control.

                                                            ii.      The Customer is solely responsible for proper synchronization of its generator with BTU’s system.

                                                          iii.      The excitation system response ratio shall not be less than 0.5.

                                                          iv.      The generator’s excitation system shall conform to the field voltage versus time criteria specified in ANSI Standard C50.13-1989.

b.      Induction generator

                                                              i.      The induction generator used for generation may be brought up to synchronous speed if it can be demonstrated that the initial voltage drop at the point of interconnection is within the flicker limits specified in this document.

c.       Inverters

                                                              i.      Line-commutated inverters do not require synchronizing equipment.

                                                            ii.      Self-commutated inverters require synchronizing equipment.

13.  Conformance to standards  

The distributed generation equipment shall be designed, installed, operated and maintained in accordance with, but not limited to, ANSI standards, UL standards, IEEE standards, the National Electrical Code, ERCOT Operating Guides and any other applicable local, state or federal codes and statutes. In the case of a conflict between the requirements in this document and any of those standards or codes, this document shall prevail.

Adopted:  4-07-08