R-1 — لوائح التركيبات الكهربائية
8 المحركات الكهربائية ودوائرها وأجهزة التحكم
الصفحة 36 في الوثيقة الأصلية
عرض PDFSECTION 8
ELECTRIC MOTORS, MOTOR CIRCUITS AND CONTROLLERS
801 All motors shall generally be totally enclosed, fan -cooled. Other types of enclosures may be
employed provided that they are suitable for the particular application.
802 All motors, control gears and all ancillary apparatus (e.g. remote push buttons, pressure, float or limit
switches, interlocks, relays, etc.) shall be of robust construction and shall have all windings, contacts and all
current carrying live parts and components insulated with Class 'E' or "B' materials. For certain
applications and locations other superior classes of insulating materials may be applicable, and each
situation shall be carefully studied in order to ensure that the temperature rise of the motor as declared by
the manufacturer + ambient temperature is at least 10°C below the maximum operating temperature of the
Insulating material used.
NOTES: I: The ambient temperatures in plant rooms should be taken as SS'C.
2: In all cases where the motors depend totally on the outside air for cooling whether
by natural ventilation or by mechanical ventilation of the motor room, the entering
cooling air temperature shall be taken as not less than 48'C for the purpose of
Calculating the amount of ventilating air.
803 Motors and their control gears shall be located so that adequate ventilation is provided and so that
inspection and maintenance can be readily accomplished.
804 If any motor is to be located out of doors, such motor shall be protected from overheating by the sun
with a canopy of approved design.
805 Motors below 1 H.P. may be connected to single phase supply. Under special conditions to be approved
by M.E.W for each individual case, motors upto 5 H.P. may be connected to single phase supply. No motor
higher than 5 H.P. shall be connected to single phase.
EXCEPTION: The Air-conditioning units approved by the Ministry with motors for 3-phase supply
but of rating 5HP or less shall be connected to three phase supply.
806 Self-contained air conditioning units upto 2.5 KW may be connected to a single phase supply.
807 Motors up to 150 H.P. may be connected to the 415 volts supply system. Where a consumer proposes
to use motors of higher capacity, he should contact the M.E.W. to obtain the approval of such supply before
purchasing any motor or appliance. If power supply at voltages higher than 415 volts are required. M.E. W.
can only supply 11000 volts, 3 phase, 50 Hz.
808 3-Phase motors up to and including15 H.P. may be started direct on line (D.O.L.). Motors above
15 H.P. shall be provided with equipment to ensure that starting current does not exceed 2.5 time the full load
current. For larger motors, method of starting and voltage dips must be discussed with and approved by
M.E.W. in each case before the motors are connected to power supply.
809 All motors over 1H.P. shall be provided with starters which have means for automatically
disconnecting them from the electric supply in the event of:
Failure of supply, Serious drop in voltage, Flow of excess current
EXCEPTION: For motors driving fire pumps, the above protections may be omitted. Where no volt releases
are fitted to such motors they shall be of the automatic resetting type.
810 Each motor over 1 H.P. shall be provided wi th means of isolation suitably placed and so connected that
all voltage may be cut off from the motor and all apparatus including any automatic circuit breaker used
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there with, If this means of isolation is remote from a motor, an additional means of isolation adjacent to the
motor shall be installed. This means of isolation may be an isolator or "stop-lock" button.
811 Where a group of motors function as one unit, means shall be provided in the control system, to prevent
the simultaneous starting of all motors at one and the same time. Where this is not possible for any reason
whatsoever, then the method of starting shall be approved by the M.E.W.
812 Starters shall be provided with over load relays of the thermal type with automatic compensation for
variation in ambient temperature between 0°C and 55°C.
813 All starters and push buttons shall be clearly labeled in Arabic and English stating the machines they
control and the function of the various buttons.
STOP push buttons shall have large mush room heads and/or colored bright red.
START push buttons shall be shrouded to prevent accidental operation and must be colored green.
814 All motors, single phase and three phase, shall have a power factor according to clause 314 at full load.
Final circuit conductor sizes for motors shall be selected in accordance with the method indicated in Section 15.
815 All motors shall be suitably earthed in accordance with the requirements set out in Section 6.
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ELECTRIC MOTORS, MOTOR CIRCUITS AND CONTROLLERS
801 All motors shall generally be totally enclosed, fan -cooled. Other types of enclosures may be
employed provided that they are suitable for the particular application.
802 All motors, control gears and all ancillary apparatus (e.g. remote push buttons, pressure, float or limit
switches, interlocks, relays, etc.) shall be of robust construction and shall have all windings, contacts and all
current carrying live parts and components insulated with Class 'E' or "B' materials. For certain
applications and locations other superior classes of insulating materials may be applicable, and each
situation shall be carefully studied in order to ensure that the temperature rise of the motor as declared by
the manufacturer + ambient temperature is at least 10°C below the maximum operating temperature of the
Insulating material used.
NOTES: I: The ambient temperatures in plant rooms should be taken as SS'C.
2: In all cases where the motors depend totally on the outside air for cooling whether
by natural ventilation or by mechanical ventilation of the motor room, the entering
cooling air temperature shall be taken as not less than 48'C for the purpose of
Calculating the amount of ventilating air.
803 Motors and their control gears shall be located so that adequate ventilation is provided and so that
inspection and maintenance can be readily accomplished.
804 If any motor is to be located out of doors, such motor shall be protected from overheating by the sun
with a canopy of approved design.
805 Motors below 1 H.P. may be connected to single phase supply. Under special conditions to be approved
by M.E.W for each individual case, motors upto 5 H.P. may be connected to single phase supply. No motor
higher than 5 H.P. shall be connected to single phase.
EXCEPTION: The Air-conditioning units approved by the Ministry with motors for 3-phase supply
but of rating 5HP or less shall be connected to three phase supply.
806 Self-contained air conditioning units upto 2.5 KW may be connected to a single phase supply.
807 Motors up to 150 H.P. may be connected to the 415 volts supply system. Where a consumer proposes
to use motors of higher capacity, he should contact the M.E.W. to obtain the approval of such supply before
purchasing any motor or appliance. If power supply at voltages higher than 415 volts are required. M.E. W.
can only supply 11000 volts, 3 phase, 50 Hz.
808 3-Phase motors up to and including15 H.P. may be started direct on line (D.O.L.). Motors above
15 H.P. shall be provided with equipment to ensure that starting current does not exceed 2.5 time the full load
current. For larger motors, method of starting and voltage dips must be discussed with and approved by
M.E.W. in each case before the motors are connected to power supply.
809 All motors over 1H.P. shall be provided with starters which have means for automatically
disconnecting them from the electric supply in the event of:
Failure of supply, Serious drop in voltage, Flow of excess current
EXCEPTION: For motors driving fire pumps, the above protections may be omitted. Where no volt releases
are fitted to such motors they shall be of the automatic resetting type.
810 Each motor over 1 H.P. shall be provided wi th means of isolation suitably placed and so connected that
all voltage may be cut off from the motor and all apparatus including any automatic circuit breaker used
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there with, If this means of isolation is remote from a motor, an additional means of isolation adjacent to the
motor shall be installed. This means of isolation may be an isolator or "stop-lock" button.
811 Where a group of motors function as one unit, means shall be provided in the control system, to prevent
the simultaneous starting of all motors at one and the same time. Where this is not possible for any reason
whatsoever, then the method of starting shall be approved by the M.E.W.
812 Starters shall be provided with over load relays of the thermal type with automatic compensation for
variation in ambient temperature between 0°C and 55°C.
813 All starters and push buttons shall be clearly labeled in Arabic and English stating the machines they
control and the function of the various buttons.
STOP push buttons shall have large mush room heads and/or colored bright red.
START push buttons shall be shrouded to prevent accidental operation and must be colored green.
814 All motors, single phase and three phase, shall have a power factor according to clause 314 at full load.
Final circuit conductor sizes for motors shall be selected in accordance with the method indicated in Section 15.
815 All motors shall be suitably earthed in accordance with the requirements set out in Section 6.
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