semi合集-English.pdf - 第7128页

SEMI S22-1103a © SEMI 2003, 2005 13 b) the connections should be lo cated within the m ain electrical enclosur e located near the top, with adequate bending space p rovided for sup ply conductor installatio n and no equi…

SEMI S22-1103a © SEMI 2003, 2005 12

9.1.6 Identification of Facilities Connections

9.1.6.1 Where a neutral conductor is used it should be clearly indicated in the equipment schematic drawings and

the facilities supply connection should be labeled “N” or “Neutral”.

EXCEPTION: This marking is not necessary in cord connected equipment where the cord is not installed in the

field.

9.1.6.2 At each incoming supply point, the protective earthing conductor terminal should be identified by the

earthing symbol (see IEC 60417 symbol 5019). In addition to the earthing symbol, other appropriate letter

designations may be applied (e.g. “PE”, “GND”).

9.1.6.3 Installation instructions should be provided for the correct identification and installation of the individual

phases in a three phase system when the improper connection of phases could result in hazardous unintended

rotation or sequence.

9.1.6.4 Each unearthed phase conductor in 3 phase AC power circuits should be clearly indicated in the equipment

schematic drawings, and the facilities incoming supply connection should be identified with one of the following

schemes adjacent to the input terminals:

a) “L1”, “L2”, and “L3",

b) “R”, “S”, and “T”, or

c) “A”, “B”, and “C”.

9.2 Equipment Protective Earthing Connection

9.2.1 A protective earthing conductor should enter the equipment in association with the incoming supply

conductors.

9.2.2 The protective earthing conductor should be copper.

9.2.3 The protective earthing conductor should be sized in accordance with the tables in Appendix 1. See Appendix

1, Tables A1-1 through A1-5 for protective earthing conductor sizes.

9.2.4 The protective earthing conductor terminal should be dedicated for the sole purpose of connecting the

protective earthing conductor to the equipment protective conductors and bonding system.

9.2.5 The protective earthing conductor and its connection to the protective earthing conductor terminal should also

comply with the protective bonding section of this safety guideline (§12).

9.2.6 The protective earthing conductor should not be used as an intentional current carrying conductor for the

power delivery circuit. Currents on the protective earthing conductor from EMC filters are permissible. The

protective earthing conductor may also carry currents that result from incidental inductive and capacitive coupling.

9.2.7 There should be no connection between the supply neutral conductor and the protective earthing conductor or

the protective earthing system inside the electrical equipment.

9.3 Main Disconnecting Means

9.3.1 The main energy isolation capabilities (equipment main disconnecting means) should be in a location that is

readily accessible and should be lockable only in the de-energized position.

9.3.2

For equipment with multiple incoming electrical feeds, all of the main disconnecting means should be

grouped in one area or a marking should be installed at each supply circuit main disconnecting means location

indicating the number of all other supply circuit main disconnecting means.

NOTE 22: Grouping main disconnecting means in one area is preferred.

9.3.3 Supply conductor connections to the main disconnecting means should comply with one of the following:

a) the connections should be located in a separate electrical enclosure installed on or adjacent to the equipment

enclosing the main disconnecting means only. Parts on the supply side of the main disconnecting means in

the equipment which remain energized when the main disconnecting means is switched off should be guarded

(finger-safe) to prevent accidental contact by service personnel; or

SEMI S22-1103a © SEMI 2003, 2005 13

b) the connections should be located within the main electrical enclosure located near the top, with adequate

bending space provided for supply conductor installation and no equipment located above the supply

terminals. Parts on the supply side of the main disconnecting means in the equipment which remain energized

when the main disconnecting means is switched off should be guarded (finger safe) to prevent accidental

contact by service personnel; or

c) the connections should be located within the main electrical enclosure, where other equipment is mounted

above the supply terminals. Parts on the supply side of the main disconnecting means in the equipment which

remain energized when the main disconnecting means is switched off should be guarded to prevent accidental

contact by service personnel or by a tool that may be dropped from above. The opening should be such that a

1-mm (0.04 inch) rod cannot come into contact with the energized parts.

EXCEPTION: Machines with a power consumption totaling 1492 Watts (2 HP) or less may be connected to a

remotely mounted main disconnecting means through a flexible cord, cable, or conduit provided that the main

disconnecting means is in sight from, readily accessible to, and no more than 6 m (20 feet) from the machine

operator work station.

9.3.4 Wire bending space should be provided for the facility supply conductors at the main disconnecting means as

specified by Appendix 1, Tables A1-1 through A1-5.

EXCEPTION: Equipment that meets the wire bending space requirements of NFPA 70 will also meet these criteria.

9.3.5 When placed in the off position the main disconnecting means should satisfy the following criteria:

a) All unearthed conductors of the supply circuit should be disconnected simultaneously.

b) Earthed conductors (neutral or grounded) should not be disconnected.

EXCEPTION: The earthed conductor (neutral) may be disconnected provided that it is disconnected simultaneously

with the unearthed conductors.

NOTE 23: Some jurisdictions require disconnection of the earthed conductor (neutral).

9.3.6 The main disconnecting means should have a minimum of two marked positions, “Off” (isolated) and “On”.

These positions should be clearly marked with IEC 60417 symbol 5008 for “Off” and IEC 60417 symbol 5007 for

“On”.

9.3.7 The actuator of the equipment’s main disconnecting means should be readily accessible and a maximum of 2

meters above the standing surface, measured from the center of the grip.

9.3.8 Each facility main disconnecting means for the incoming electrical supply should be mechanically or

electrically interlocked, or both, with the electrical disconnect enclosure door.

EXCEPTION 1: A main disconnecting means used only for maintenance of lighting circuits within electrical

enclosures should not be interlocked with the electrical enclosure door. A hazard warning label should be provided

when exposed parts may be energized within the main disconnect enclosure when the enclosure door is open.

EXCEPTION 2: Where an attachment plug is used as the main disconnecting means.

EXCEPTION 3: Where a remotely mounted main disconnecting means is provided, a tool is required to open the

equipment enclosure door, and a hazard warning label is attached to the electrical enclosure warning of hazardous

voltage inside and advising isolation of the power before opening.

EXCEPTION 4: The considerations stated in ¶9.3.8 do not apply to equipment rated less than 5KVA that has the

other protections against electric shock stipulated in this document.

9.3.9 The main disconnecting means (lock-out) handle should not disengage from the main disconnecting means

when the enclosure door is opened.

9.3.10 Interlocking should be provided between the main disconnecting means and its associated door to prevent

both of the following:

a) closing of the main disconnecting means while the enclosure door is open, unless the interlock

disconnecting power is overridden by a deliberate action (see §13), and

b) closing of the main disconnecting means until the door hardware is fully closed.

NOTE 24: A mechanical interlock is preferable to an electrical interlock.

9.4 Cord and Plug Connections used as Facility Connection

9.4.1 When a cord and plug connection is intended to be used as a main disconnecting means, it should either be

capable of being under the exclusive supervision of the person carrying out the work, or be provided with a means

for lockout (see discussion of conductors and cables in §16).

9.4.2 If a supply cord is provided with the system, the cord, as well as the installation instructions, should comply

with applicable local codes where it will be installed, or the equipment should have provisions for hard wiring using

a raceway.

9.4.3 If there are provisions for hard wiring, a cord and plug should not be used as a main disconnecting means.

9.4.4 If the cord and plug is used for the main disconnecting means the equipment should also have an on-off

control.

NOTE 25: Uses preferred for cord and plug connection to the facility include:

a) equipment with an attachment plug and powered from a receptacle outlet to connect movable equipment to facilitate

frequent interchange, and

b) the fastening means and mechanical connections of the equipment are designed to permit removal for maintenance or

service.

NOTE 26: Materials are restricted by ¶16.3.1.

10 Protection Against Electric Shock

10.1 General  The electrical equipment should provide protection to persons against electric shock under normal

operating conditions and under any reasonably foreseeable single fault condition.

10.2 Protection Against Electric Shock During Normal Operation

10.2.1 Where operator access to a hazardous voltage is controlled through the use of a grounded conductive or non-

conductive enclosure, that enclosure should either:

1) require a tool to open and be labeled with the hazard against which it protects personnel, or

2) be interlocked.

Reference Jointed Finger Probe Access Test. Reference IEC61010-1 Annex B for the test finger.

NOTE 27: IEC 60529 “Degrees of Protection Provided by Enclosures” may be used as a reference.

10.2.2 Spacing between uninsulated energized parts and conductive enclosures should be maintained in compliance

with Appendix 1 Tables A1-12 and A1-13 or determined to be adequate by dielectric testing in accordance with §22.

10.2.3 Energized parts protected by insulation should be completely covered with insulation that can be removed

only by destruction. Such insulation should be capable of withstanding the mechanical, chemical, electrical, and

thermal stresses to which it may be subjected under normal operation.

10.2.4 Protection Against Electric Shock Hazards Resulting from Fault Conditions — Use of measures to prevent

the occurrence of a hazardous touch voltage may include one or more of the following:

a) Double or reinforced insulation may be used to prevent a hazardous touch voltage through contact with

exposed conductive parts that results from the failure of basic insulation of the energized parts of that circuit,

b) Electrical separation (clearance and creepage) may be used to prevent a hazardous touch voltage through

contact with exposed conductive parts that results from the failure of basic insulation of the energized parts of

that circuit,

c) Automatic disconnection of the supply of any circuit affected by the occurrence of an insulation failure that

results in a ground fault may be used to prevent contact with a hazardous voltage.

NOTE 28: See definition of GFCI.