1、INTERNATIONAL STANDARD IS0 12374 First edition 1995-07-I 5 ANSI internat Woe Sw Agricultural irrigation - Wiring and equipment for electrically driven or controlled irrigation machines Irrigation agricole - Gblage et mat however, the allowable current is set to pre- vent overheating and damage to in
2、sulation or equipment. 3.2 auxiliary conductor: Conductor that carries current to a device which is not necessary for move- ment of the machine. 3.3 auxiliary panel: Enclosure containing auxiliary control devices for the machine such as motor con- trollers, relays, switches and transformers, but not
3、 including the main controller and other main control devices that supply power to the entire machine. NOTE 2 A junction box is not an auxiliary panel. 3.4 bonded connection: Reliable connection to en- sure the necessary electrical conductivity between metal parts required to be electrically connect
4、ed. 3.5 collector ring: Assembly of slip rings for trans- ferring electrical energy from a stationary conductor to a rotating conductor. 3.6 control conductor: Conductor that carries cur- rent to a control device that is necessary for move- ment of the machine. 3.7 front-mounted device: Replaceable
5、device mounted so that it may be individually replaced from the front of an enclosure without removing subpanels, 1 IS0 12374:1995(E) 0 IS0 other devices or rear enclosure covers to gain access to hidden fasteners. 3.8 front-wired device: Replaceable device mounted so that it may be individually wir
6、ed from the front of an enclosure without removing the device, subpanels or rear enclosure covers to gain access to electrical connections. 3.9 grounded: Connected to earth or to some con- ducting body which serves in place of earth. 3.10 grounded conductor: Conductor in a circuit which is intention
7、ally grounded. 3.11 grounding conductor: Conductor used to connect non-current-carrying metal parts of a machine to a service-grounded conductor and/or a grounding- electrode conductor. 3.12 (irrigation) machine: Electrically driven or controlled machine, not portable by hand, used pri- marily to tr
8、ansport and distribute water for agricultural purposes. 3.13 machine isolator: Disconnecting means at the point of connection of electrical power to the ma- chine. 3.14 main control panel: Enclosure containing the main controller and other control devices necessary for starting and stopping the mach
9、ine. 3.15 metal-to-metal connection: Attachment of metal parts to the machine with bolts and screws to provide an adequate contact for bonding purposes where all paint and dirt have been removed from under the bearing surface area of bolt or screw heads. 3.16 nonwicking filler: Filler material withi
10、n an electrical cable which has high resistance to moisture migration from one location to another within the cable. 3.17 power conductor: Conductor that carries cur- rent to provide electrical power from the machine isolator to a drive motor. 3.18 raceway: Enclosed channel designed expressly for ho
11、lding electrical wires, cables or busbars. 3.19 readily accessible: Capable of being opened quickly for maintenance, repair or inspection. NOTE 3 The object may be fastened by latches or held by mechanical interlocks or similar apparatus. A cover firmly attached by two or more screws is not consider
12、ed readily accessible. 3.20 weatherproof: Constructed or protected so that exposure to the environment does not interfere with successful operation. 4 General requirements 4.1 Means of isolation A mechanism to provide overcurrent protection to a machine with the capacity to lock the machine in the O
13、FF position shall be provided at the point of con- nection of electrical power to the machine. 4.2 Enclosures 4.2.1 All enclosures shall have a degree of pro- tection of IP 33 as specified in IEC 529. 4.2.2 Entrances into, exits from, and penetrations of the enclosure shall be made such as to reduce
14、 the possibility of the collection of water or contaminants at the point of connection and to preserve the rating of the enclosure specified in 4.21. 4.2.3 Dimensions of enclosures shall not be less than the maximum dimensions of the enclosed equipment plus the required electrical clearances which c
15、onform to the requirements in IEC 529. 4.2.4 Where used, gaskets shall be securely at- tached to one of the mating parts. 4.2.5 Enclosures should be mounted such as to minimize the possibility of subsequent physical dam- age to the enclosure. 4.3 Interlocking Where personal hazard or property damage
16、 may be caused by the failure of any device to function prop- erly, protective interlocks, shall be provided. Where practicable, these interlocks shall interrupt all oper- ations, providing such interruption does not create a hazardous condition. 4.4 Automatic or remote starting 4.4.1 Automatic rest
17、arting shall be connected so that restarting occurs only on resumption of full single-phase or three-phase power, as needed, fol- lowing a power cut or upon resumption of fluid pressure. Automatic restarting shall not be construed as en- compassing the functions of a device or circuit de- 2 0 IS0 IS
18、0 12374:1995(E) signed for reversing the direction of travel of the machine at a preset point or points. 4.4.2 Machines equipped with automatic restarting or remote starting shall have affixed to the machine a safety sign indicating that the machine can start automatically. 4.4.2.1 This safety sign
19、shall be affixed to the ma- chine isolator. It shall also be affixed to the main control panel if the machine isolator is not part of or adjacent to the main control panel. 4.4.2.2 The wording and size of this sign shall be as specified in clause 11. 4.5 Identification All conductors within an enclo
20、sure shall be clearly marked or colour-coded for identification as specified in 9.6. 4.6 Transformer type Transformers shall be of the isolated type with proper overcurrent protection for the transformer, and con- ductors or control devices it serves. 4.7 Conductor rating Terminal blocks or strips s
21、hall be sized to accommo- date the number and size of the conductors termin- ated or connected to them, and shall be rated for the voltage and current transmitted on the connected or terminated conductors. 4.8 Control device rating Control devices such as relays, limit switches and similar equipment
22、 shall be suitable for the application and shall be capable of handling the voltage and cur- rent imposed on or through the devices. 4.9 Panel mounting Panel-mounted devices shall be front-mounted and front-wired for convenient servicing. 4.10 Current ratings 4.10.1 All machines except centre-pivot
23、machines Where a machine is multimotored and individual motors are controlled by alignment switches or similar devices, where the machine does not operate in a circle and where intermittent duty is inherent, the continuous-current rating and peak-current rating shall be determined as follows. 4.10.1
24、.1 The equivalent continuous-current rating shall be calculated as 125 % of the full-load current rating of the largest motor plus a quantity equal to the sum of the full-load current ratings of all remaining motors multiplied by the maximum percent duty cycle factor at which the remaining motors ca
25、n continuously operate. 4.10.1.2 The peak-current rating shall be calculated as the sum of the locked-rotor current of the two largest motors plus 100 % of the full-load current ratings of all other motors in the circuit. 4.10.2 Centre-pivot machines Where a machine is multimotored and individual mo
26、tors are controlled by alignment switches or similar devices, where the machine operates in a circle and where intermittent duty is inherent, the continuous- current rating and the peak-current rating shall be de- termined as follows. 4.10.2.1 The equivalent continuous-current rating shall be calcul
27、ated as 125 % of the full-load current rating of the largest motor plus 60 % of the sum of the full-load current ratings of the remaining motors. 4.10.2.2 The peak-current rating shall be calculated as twice the locked-rotor current of the largest motor plus 80 % of the sum of the full-load current
28、ratings of the remaining motors. 5 Grounding 5.1 A grounding conductor used for no other pur- poses than machine grounding shall be provided. 5.1.1 The grounding conductor shall be bonded to the machine within the main control panel enclosure and each auxiliary panel enclosure. 5.1.2 The grounding c
29、onductor shall be within the same sheath, jacket or conduit as the power, control or auxiliary conductors. 5.1.3 The grounding conductor may be bare or insu- lated as specified in 9.6.2.1. 5.1.4 The metallic sheath of any cable or metallic conduit shall not be used as the primary grounding conductor
30、. 3 IS0 12374:1995(E) 0 IS0 5.2 Metal-to-metal connection to a part which is bonded to the grounding conductor and the non- current-carrying parts of the machine shall be con- sidered as an adequate grounding path. 5.3 The metallic sheath of cable or metallic conduit, where used, shall be grounded.
31、5.4 External metal parts which could become inad- vertently energized shall be grounded. 5.5 Motor frames shall be bonded to the grounding conductor. 5.6 Metal frames of devices such as switches, solenoids and junction boxes shall be bonded to the grounding conductor or to the non-current-carrying m
32、etal parts of the machine. 5.7 The grounding conductor shall not have less ampacity than its associated power conductors. Where there is a reduction of conductor size because of the use of an interposing relay, controller or similar device, the grounding conductor may also be reduced to the same siz
33、e as the power, control or auxiliary conductors originating at the interposing device. 5.8 Where a machine has a stationary point, such machine shall include provision for the connection of the machine-grounding conductor to the grounding- electrode conductor. Proper installation of the grounding-el
34、ectrode conductor shall complete an electrical path from the machine-grounding conductor to the grounding electrode. 58.1 A prominently displayed durable sign shall be permanently affixed to the main control panel which indicates the need for proper grounding. 5.8.2 The installation and operating in
35、structions for the machine shall include specific recommendations for connecting or installing the grounding electrode. 5.9 A common connection device for all grounding conductors shall be provided. 6 Main control panel 6.1 Enclosure The enclosure for the main panel shall conform to 4.2. 6.2 Means o
36、f isolation 6.2.1 If the means to isolate a machine is not in or adjacent to the main control panel, an isolating mechanism which makes it possible to lock the ma- chine in the OFF position shall also be provided in or adjacent to the main control panel. 6.2.2 If the main control panel is remote fro
37、m the machine, a disconnecting mechanism which makes it possible to lock the machine in the OFF position shall be provided at the machine for removing power from all circuits of 30 V or more. 6.2.3 If the main control panel contains a means of isolation, the panel shall be interlocked with the en- c
38、losure opening. Means may be provided for qualified persons to gain access to enclosures without removing power if the interlocking is reactivated automatically when the en- closure is closed. 6.2.4 If a means of isolation is adjacent to the main control panel and live parts of components are not re
39、adily accessible, the interlock in the enclosure opening is not required. It is recommended, however, that interlocking be provided. 6.2.5 Equipment within an enclosure receiving elec- trical energy from more than one source shall not be required to have a means of isolation for the additional sourc
40、e provided its voltage is 30 V or less and its power level not more than 1 000 V-A. 6.3 Doors Hinged doors for enclosure openings shall have a mechanical stop to prevent strain on conductors and terminals contained in or on the door. Conductors to components or terminals contained in or on the hinge
41、d door shall be fastened so that any conductor flexing occurs at the fastener and not at conductor terminals. 6.4 Limitation The main control panel shall not be used as a raceway. 6.5 Locking attachment 6.5.1 Attachment plugs and receptacles shall be of a standardized locking type to prevent accidental iso- lation and shall be of proper design for the voltage, current and environment for which they are used.
