semi合集-English.pdf - 第7122页
SEMI S22-1103a © SEMI 2003, 2005 7 5.1.50 permanently connected equipment — equi pment that is electrically co nn ected to a supply by m eans of a connection that may be detac hed only by the use of a t ool. 5.1.51 pollu…
SEMI S22-1103a © SEMI 2003, 2005 6
5.1.34 hazardous electrical power — power levels equal to or greater than 240VA.
5.1.35 insulation — a layer of non-conductive material used as the outer surface of a conductor for the purpose of
protecting against electric shock.
5.1.36 interlock — a mechanical, electrical or other type of device or system, whose purpose is to prevent or
interrupt the operation of equipment subsystems under specified conditions.
5.1.37 interrupting capacity — the highest current at rated voltage that a device is intended to interrupt.
NOTE 7: Also known as amperes interrupting capacity (AIC).
5.1.38 isolated power system — a power system that has a high impedance between its conductors and the facilities
connection of the equipment. High impedance can be characterized by resistances of one meg-ohm or more.
Isolated power systems are supplied power by isolation transformers or power supplies that have no direct electrical
connection between their primary conductors and their secondary conductors.
NOTE 8: An isolation transformer with one leg of the secondary connected to ground is not an isolated power system.
5.1.39 main disconnecting means — a disconnecting means that is intended to be used to disconnect facilities
electrical power from the system.
5.1.40 maintenance — planned activities intended to keep equipment in proper working order (see also the
definition for service).
5.1.41 material group — a categorization of the Comparative Tracking Index (CTI) of an insulator as follows:
Material Group I: 600 <= CTI
Material Group II: 400 <= CTI < 600
Material Group IIIa: 175 <= CTI < 400
Material Group IIIb: 100 <= CTI < 175
5.1.42 maximum nominal load — the maximum continuous power a circuit will draw under operating conditions
prescribed by the manufacturer. Non-periodic power variations of less than a second in duration are not considered
continuous.
5.1.43 multi-outlet assemblies — assemblies whose primary function is to provide electrical connections and that
have multiple receptacles which are intended for electrical connections.
5.1.44 neutral conductor — an earthed (grounded) AC current carrying conductor.
NOTE 9: It is distinct from protective earthing which is an earthed (grounded) non-current carrying conductor or a non-earthed
(non-grounded) current carrying conductor.
5.1.45 normal operating conditions — the condition of the equipment reasonably foreseen by the manufacturer,
including specified conditions of use, during operation, maintenance and servicing while the equipment is operated,
maintained and serviced according to the manufacturer’s instructions and with no unauthorized equipment
modifications. Normal operating conditions should include consideration of reasonably foreseeable misuse.
5.1.46 operator — a person who interacts with the equipment only to the degree necessary for the equipment to
perform its intended function.
5.1.47 operator access — an area to which, under normal operating conditions, one of the following applies: access
may be gained without the use of a tool, the means of access is deliberately provided to the operator, or the operator
is instructed to enter regardless of whether or not a tool is needed to gain access (if the operator is so instructed, this
area becomes evaluatable as an operator accessible area).
5.1.48 overcurrent — any current in excess of the rated current of the equipment or the rated ampacity (current-
carrying capacity) of the conductor; it may result from overload, short circuit, or ground fault.
5.1.49 overload — operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated
ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A
fault, such as a short circuit or ground fault, is not an overload (see short circuit and ground fault).
SEMI S22-1103a © SEMI 2003, 2005 7
5.1.50 permanently connected equipment — equipment that is electrically connected to a supply by means of a
connection that may be detached only by the use of a tool.
5.1.51 pollution — any addition of foreign matter, solid, liquid or gas, that may produce a reduction of dielectric
strength or increase of surface resistivity.
5.1.52 pollution degree — for the purpose of evaluating clearances the following two degrees of pollution in the
micro-environment are recognized for use with this document:
5.1.52.1 pollution degree 1 — no pollution or only dry, non-conductive pollution occurs. The pollution has no
influence. Cleanroom Class 1000 or less.
NOTE 10: Cleanroom Class 1000 or less is pollution degree 1, however the pollution degree in a particular area in a given piece
of equipment may exceed pollution degree 1, even if the equipment is installed in a cleanroom class 1000 or less.
5.1.52.2 pollution degree 2 — normally only non-conductive pollution occurs. Occasionally, however, a temporary
conductivity caused by condensation is expected. Cleanroom Class greater than 1000.
NOTE 11: Cleanroom Class greater than 1000 is pollution degree 2, however the pollution degree in a particular area in a given
piece of equipment may exceed pollution degree 2, even if the equipment is installed in a cleanroom greater than 1000.
5.1.53 protective conductor — a conductor that provides electrical continuity between conductive components that
are not intended to be energized during normal operations and the equipment’s protective earthing conductor
terminal.
5.1.54 protective earthing conductor — a normally non-current carrying conductor connected between earth
(ground) at the source of supply and the protective earthing (grounding) terminal on the equipment enclosure.
5.1.55 protective earthing conductor terminal — a terminal bonded to conductive parts of an equipment enclosure
for safety purposes and intended to be connected to an external protective earthing (grounding) conductor (the
protective earthing conductor).
5.1.56 protective earthing system — the earthing (grounding & bonding) system connecting accessible conductive
parts of the equipment to an external earth (ground) at the source of supply. The protective earthing system may
include bonded structural members, bonding jumpers, the protective earthing conductor terminal on the equipment
and the protective earthing conductor in the incoming supply wiring to the equipment.
5.1.57 raceway — an enclosed channel of metal, or nonmetallic materials, designed expressly for holding wires,
cables, or busbars.
5.1.58 readily accessible — capable of being reached quickly for operation or inspection, without requiring
climbing over or removing obstacles or using portable ladders, chairs, etc.
5.1.59 reinforced insulation — a single layer of insulation that provides a degree of protection against electric shock
equivalent to double insulation.
5.1.60 risk — the expected losses from a mishap, expressed in terms of severity and likelihood.
5.1.61 safe shutdown condition — a condition in which all hazardous energy sources and hazardous production
materials are removed or suitably contained, unless this results in additional hazardous conditions.
5.1.62 safety circuit — a circuit whose intended function is to make the equipment safer. Interlocks, EMO circuits,
and other protective circuits are safety circuits.
5.1.63 service — unplanned activities intended to return equipment that has failed to proper working order (see also
maintenance).
5.1.64 severity — the extent of the worst credible loss (damage, injury, or release) from a mishap caused by a
specific hazard.
5.1.65 supplementary insulation — applied to basic insulation in order to ensure protection against electric shock in
the event of the failure of basic insulation.
5.1.66 testing — measurements or observations used to validate and document conformance to designated
criteria.
5.1.67 tool — an external device used to aid a person to perform a mechanical function.
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5.1.68 types of electrical work — defined by the electrical energy levels a person is exposed to when performing a
task. All tasks that should be performed on a system fall into one of the four following type categories of electrical
work:
5.1.68.1 type 1 — equipment is fully de-energized.
5.1.68.2 type 2 — equipment is energized. Energized circuits are covered or insulated with no exposed parts.
NOTE 12: Type 2 work includes those tasks where the energized circuits are, or may be, measured by placing probes through
suitable openings in the covers or insulators.
5.1.68.3 type 3 — equipment is energized. Energized circuits are exposed and inadvertent contact with un-insulated
energized parts is possible. Potential exposures are not greater than 30 Volts rms, 42.4 Volts peak, 60 Volts DC, and
240 volt-amps in dry locations.
5.1.68.4 type 4 — equipment is energized. Energized circuits are exposed and inadvertent contact with un-insulated
energized parts is possible. Potential exposures are greater than 30 Volts rms, 42.4 Volts peak, 60 Volts DC, 240
volt-amps in dry locations, or where induced or contact radio-frequency currents exceed the limits in SEMI S2.
5.1.69 wire guide — any method of mechanically securing wire or cable into a restrictive routing.
6 Alternate Methods of Conformity
6.1 The criteria in this document are based on harmonized basic electrical safety considerations. It is not the intent
of this document to be the only means of demonstrating the electrical safety conformance of semiconductor
manufacturing equipment.
6.2 Equipment that satisfies other national or international electrical product safety standards meets the intent of this
document.
7 Design Philosophy
NOTE 13: This section is intended to provide general design guidance to engineers; for specific design considerations see §8
through §22.
7.1 This document should be used during the electrical design, construction, and evaluation phases of
semiconductor manufacturing equipment. The intent of this safety guideline is to provide a design based electrical
document that will be useful to both design engineers and evaluators, in order to facilitate electrical safety in the
equipment.
7.2 Designers that understand these general principles of safety are more likely to design safe equipment. This
section is not an alternative to the more specific engineering considerations of this safety guideline, but is intended
to provide designers with an appreciation of the basic safety principles.
7.3 Electric shock is due to current passing through the human body. Currents on the order of a milliampere may
cause a reaction in people in good health, and may cause indirect mishap due to involuntary reactions. Higher
currents may have higher severity risks.
7.4 Design of equipment should provided protection of personnel from electric shock or arc flash/blast that may
result from reasonably forseeable single faults.
7.5 Service and maintenance personnel should be protected against inadvertent contact with electrical hazards.
7.6 Movable cord-connected equipment is considered to present a slightly increased risk of shock as well as
overheating, due to strain on the supply cord leading to damage to the connections, insulation, and the protective
earthing conductor. With portable cord-connected equipment, wear on the cord is more likely, and further hazards
could arise if the equipment were dropped.
7.7 Short-circuiting between phases and phase to ground of high current supplies or high capacitance circuits may
cause arcing or ejection of molten metal which may cause burns. Even low voltage circuits may be dangerous in this
respect. Protection should be provided by adequate separation, by shielding, or by using safety interlocks.
7.8 When temperatures that could cause a hazard result from overloads, component failure, insulation breakdown,
high resistance or loose connections, the risk of fire may be reduced by one or more of the following means: