Menu

Article 675

Electrically Driven or Controlled Irrigation Machines

Part I. General

  1. Scope. The provisions of this article apply to electrically driven or controlled irrigation machines, and to the branch circuits and controllers for such equipment.
  2. Definitions.

Center Pivot Irrigation Machine. A multimotored irrigation machine that revolves around a central pivot and employs alignment switches or similar devices to control individual motors.

Collector Rings. An assembly of slip rings for transferring elec‐ tric energy from a stationary to a rotating member.

Irrigation Machine. An electrically driven or controlled machine, with one or more motors, not hand-portable, and used primarily to transport and distribute water for agricultural purposes.

675.4 Irrigation Cable.

  1. Construction. The cable used to interconnect enclosures on the structure of an irrigation machine shall be an assembly
    of stranded, insulated conductors with nonhygroscopic and nonwicking filler in a core of moisture- and flame-resistant nonmetallic material overlaid with a metallic covering and jack‐ eted with a moisture-, corrosion-, and sunlight-resistant nonme‐ tallic material.The conductor insulation shall be of a type listed in Table 310.104(A) for an operating temperature of 75°C (167°F) and for use in wet locations. The core insulating mate‐ rial thickness shall not be less than 0.76 mm (30 mils), and the metallic overlay thickness shall be not less than 0.20 mm (8 mils). The jacketing material thickness shall be not less than1.27 mm (50 mils).A composite of power, control, and grounding conductors in the cable shall be permitted.
  2. Alternate Wiring Methods. Installation of other listed cables complying with the construction requirements of 675.4(A) shall be permitted.
  3. Supports. Irrigation cable shall be secured by straps, hangers, or similar fittings identified for the purpose and so installed as not to damage the cable. Cable shall be supported at intervals not exceeding 1.2 m (4 ft).
  4. Fittings. Fittings shall be used at all points where irriga‐ tion cable terminates. The fittings shall be designed for use with the cable and shall be suitable for the conditions of serv‐ ice.
  1. More Than Three Conductors in a Raceway or Cable. The signal and control conductors of a raceway or cable shall not be counted for the purpose of ampacity adjustment as required in 310.15(B)(3)(a).
  2. Marking on Main Control Panel. The main control panel shall be provided with a nameplate giving the following information:
    1. The manufacturer’s name, the rated voltage, the phase, and the frequency
    2. The current rating of the machine
    3. The rating of the main disconnecting means and size of overcurrent protection required
  3. Equivalent Current Ratings. Where intermittent duty is not involved, the provisions of Article 430 shall be used for determining ratings for controllers, disconnecting means, conductors, and the like. Where irrigation machines have inherent intermittent duty, the determinations of equivalent current ratings in 675.7(A) and (B) shall be used.
    1. Continuous-Current Rating. The equivalent continuous- current rating for the selection of branch-circuit conductors and overcurrent protection shall be equal to 125 percent of the motor nameplate full-load current rating of the largest motor, plus a quantity equal to the sum of each of the motor name‐ plate full-load current ratings of all remaining motors on the circuit, multiplied by the maximum percent duty cycle at which they can continuously operate.
    2. Locked-Rotor Current. The equivalent locked-rotor current rating shall be equal to the numerical sum of the locked-rotor current of the two largest motors plus 100 percent of the sum of the motor nameplate full-load current ratings of all the remaining motors on the circuit.
  4. ARTICLE 675 — ELECTRICALLY DRIVEN OR CONTROLLED IRRIGATION MACHINES
  1. Disconnecting Means.
    1. Main Controller. A controller that is used to start and stop the complete machine shall meet all of the following require‐ ments:
      1. An equivalent continuous current rating not less than specified in 675.7(A) or 675.22(A)
      2. A horsepower rating not less than the value from Table 430.251(A) and Table 430.251(B), based on the equivalent locked-rotor current specified in 675.7(B) or 675.22(B)
      Exception: A listed molded case switch shall not require a horsepower rating.
    2. Main Disconnecting Means. The main disconnecting means for the machine shall provide overcurrent protection, shall be at the point of connection of electric power to the machine, or shall be in sight from the machine, and it shall be readily accessible and lockable in accordance with 110.25. This disconnecting means shall have a horsepower and current rating not less than required for the main controller.Exception No. 1: Circuit breakers without marked horsepower ratings shall be permitted in accordance with 430.109.Exception No. 2: A listed molded case switch without marked horse‐ power ratings shall be permitted.
    3. Disconnecting Means for Individual Motors and Control‐ lers. A disconnecting means shall be provided to simultane‐ ously disconnect all ungrounded conductors for each motor and controller and shall be located as required by Article 430, Part IX. The disconnecting means shall not be required to be readily accessible.
  2. Branch-Circuit Conductors. The branch-circuit conduc‐ tors shall have an ampacity not less than specified in 675.7(A) or 675.22(A).
  3. Several Motors on One Branch Circuit.
    1. Protection Required. Several motors, each not exceeding 2 hp rating, shall be permitted to be used on an irrigation machine circuit protected at not more than 30 amperes at 1000 volts, nominal, or less, provided all of the following condi‐ tions are met:
      1. The full-load rating of any motor in the circuit shall not exceed 6 amperes.
      2. Each motor in the circuit shall have individual overload protection in accordance with 430.32.
      3. Taps to individual motors shall not be smaller than
      14 AWG copper and not more than 7.5 m (25 ft) in length.
    2. Individual Protection Not Required. Individual branch- circuit short-circuit protection for motors and motor control‐ lers shall not be required where the requirements of 675.10(A) are met.
  4. Collector Rings.
    1. Transmitting Current for Power Purposes. Collector rings shall have a current rating not less than 125 percent of the full- load current of the largest device served plus the full-load current of all other devices served, or as determined from 675.7(A) or 675.22(A).
    2. Control and Signal Purposes. Collector rings for control and signal purposes shall have a current rating not less than 125 percent of the full-load current of the largest device served plus the full-load current of all other devices served.
    3. Grounding. The collector ring used for grounding shall have a current rating not less than that sized in accordance with 675.11(A).
    4. Protection. Collector rings shall be protected from the expected environment and from accidental contact by means of a suitable enclosure.
  5. Grounding. The following equipment shall be groun‐ ded:
    1. All electrical equipment on the irrigation machine
    2. All electrical equipment associated with the irrigation machine
    3. Metal junction boxes and enclosures
    4. Control panels or control equipment that supplies or controls electrical equipment to the irrigation machineException: Grounding shall not be required on machines where all of the following provisions are met:
      1. The machine is electrically controlled but not electrically driven.
      2. The control voltage is 30 volts or less.
      3. The control or signal circuits are current limited as specified in Chapter 9, Tables 11(A) and 11(B).
  6. Methods of Grounding. Machines that require grounding shall have a non–current-carrying equipment grounding conductor provided as an integral part of each cord, cable, or raceway. This grounding conductor shall be sized not less than the largest supply conductor in each cord, cable, or raceway. Feeder circuits supplying power to irrigation machines shall have an equipment grounding conductor sized according to Table 250.122.
  7. Bonding. Where electrical grounding is required on an irrigation machine, the metallic structure of the machine, metallic conduit, or metallic sheath of cable shall be connected to the grounding conductor. Metal-to-metal contact with a part that is connected to the grounding conductor and the non– current-carrying parts of the machine shall be considered as an acceptable bonding path.
  8. Lightning Protection. If an irrigation machine has a stationary point, a grounding electrode system in accordance with Article 250, Part III, shall be connected to the machine at the stationary point for lightning protection.image
  9. Energy from More Than One Source. Equipment within an enclosure receiving electric energy from more than one source shall not be required to have a disconnecting means for the additional source if its voltage is 30 volts or less and it meets the requirements of Part III of Article 725.
  10. Connectors. External plugs and connectors on the equipment shall be of the weatherproof type.

Unless provided solely for the connection of circuits meeting the requirements of Part III of Article 725, external plugs and connectors shall be constructed as specified in 250.124(A).

Part II. Center Pivot Irrigation Machines

  1. General. The provisions of Part II are intended to cover additional special requirements that are peculiar to center pivot irrigation machines. See 675.2 for the definition of Center Pivot Irrigation Machine.
  2. Equivalent Current Ratings. To establish ratings of controllers, disconnecting means, conductors, and the like, for the inherent intermittent duty of center pivot irrigation machines, the determinations in 675.22(A) and (B) shall be used.
  1. Continuous-Current Rating. The equivalent continuous- current rating for the selection of branch-circuit conductors and branch-circuit devices shall be equal to 125 percent of the motor nameplate full-load current rating of the largest motor plus 60 percent of the sum of the motor nameplate full-load current ratings of all remaining motors on the circuit.
  2. Locked-Rotor Current. The equivalent locked-rotor current rating shall be equal to the numerical sum of two times the locked-rotor current of the largest motor plus 80 percent of the sum of the motor nameplate full-load current ratings of all the remaining motors on the circuit.

Last posts

Sidebar