Aerovent ES-2-06 - Manual (Page 9)

Twin City Fan Companies Engineering Supplement 2-06 9
• Plug and Plenum fans. These fans are intended for
installation in a user supplied enclosure. Twin City
Fan Companies, Ltd. rarely knows the details of
the enclosure and therefore can not provide guard-
ing based on the needs of the final installation for
these types of fans. The user must verify that the
enclosure a plug or plenum fan is located in is
compliant with EN 953 and EN 294 and EN 811.
Guards shall not be removed during fan operation as
this could cause severe injury. Guards shall not be stood
on or used to support any additional load.
Electrical Supply and Controls
Twin City Fan Companies, Ltd. does not supply elec-
trical controls. Items identified below are intended to
guide the user in supplying controls in conformance to
Annex I of the Machinery Directive and EN 14461:2005
– Industrial Fans – Safety requirements. Furthermore,
electrical installations shall fulfill the requirements of EN
60204-1 and shall be selected for compliance with the
low voltage directive. Those involved with the design
of the electrical supply and control systems should
be familiar with the above mentioned standards and
directives. Control systems including relays, contactors,
Variable Frequency Drive Units, isolating transformers,
over-current and short circuit protection devices may be
required. Relays, contactors, Variable Frequency Drive
Units, isolating transformers, over-current and short
circuit protection devices should all be in compliance
with the Low Voltage Directive. The following is a list
of some of the more common European standards that
are observed when considering compliance with the Low
Voltage Directive.
EN60742 - Isolating Transformers
EN50178 - Electronic Equipment for use in
Power Installations.
EN60730-2-10 - Motor Starting Relays.
EN60947-2-1 - Overload trips.
EN60947-3-1 - Switches, Disconnectors, Switch
Disconnectors and Fuse Combination
Units.
EN60947-4-1 - Electro-mechanical Contactors and
Motor control circuits.
EN60947-5-1 - Electromechanical control circuit
devices.
EN60947-5-5 - Low voltage switchgear and control
gear - Part 5: Control circuit devices
and switching elements - Electrical
emergency stop devices with mechan
ical latching function.
EN61810-1 - Electromechanical elementary relays -
Part 1: General and requirements.
EN60255-23 - Electrical relays - Part 23: Contact
performance.
EN60439-1 - Low Voltage Switchgear and
Switchgear Assemblies, Part 1.
EN 60034 - Rotating Electrical machines Parts 1
and 5.
Variable Frequency Drive Units come under the Low
Voltage and EMC Directives. Standards that shall be
considered for compliance with the EMC Directive are
listed below:
EN 61000-6-4: 2001 Generic Industrial Emission
Standard.
EN 55011: 1998 + A1 Conducted Emissions
Industrial (Group 1 Class A)
In addition, controls shall meet the requirements for
category 2 safety critical control systems as detailed
in EN 954-1. When a VFD is used, controls shall be
implemented to guard against the VFD causing the fan
to run above the maximum safe speed of the fan.
Wiring diagrams provided by the electrical equipment
manufacture shall be followed.
General Considerations for Controls
Intended automatic or remote restart after short term
power failure shall only be permitted if no risk exists
and if there are no other fault conditions.
Warning signs that automatic or remote start may
take place shall be provided when applicable.
After a stop caused by the safety devices indicating
hazardous conditions, restart shall only be possible by
an intentional operation of manual control.
When possible, electrical power cables connected to
fans should be routed where there is least risk of per-
sonnel tripping, walking into or falling over such items
because they have been routed in areas where person-
nel are expected to move.
If it is necessary for periodical inspection and repairs
to override the monitoring and control systems during
operation, then consideration shall be given to the provi-
sion of stand-by fans, motors or other features. This is
allowed provided that:
• The alarm system remains in operation during the
override and an alarm signal is given when the
safety limits are reached.
• Override is indicated by a clearly visible signal.
• Override is affected by auxiliaries specially installed
for that purpose, e.g. key operated switches.
Maintenance
Any maintenance requiring the guards to be removed
shall be performed while the fan is not operating.
When restarting fan after maintenance, follow operation
checklist for start up of fan.
Lockouts shall be used whenever unexpected energiz-
ing of the fan could cause a mechanical or electrical
hazard.
Motor Maintenance
The three basic rules of motor maintenance are:
1. Keep the motor clean.
2. Keep the motor dry.
3. Keep the motor properly lubricated.
Blow dust off periodically (with low pressure air) to pre-
vent motor from overheating.
If the motor is to be started after sitting for more
than a week, the resistance of the motor windings to
earth should be measured (at 500 V DC). If the resis-
tance is less than 10 megohms, the motor should be
dried until a resistance over 10 megohms is measured.
Some smaller motors are lubricated for life. Lubrication
requirements are normally attached to the motor. Use
the motor manufacturer’s recommendations for re-lubri-
cation. If this information is not available, the following
schedule may be used. Motors less than 10 HP running
about eight hours a day in a clean environment should
be lubricated once every five years; motors 15 to 40
HP, every three years. For motors in dusty or dirty envi-
ronments or running 24 hours a day: divide the service
interval by 4. Do not over lubricate. Note that motors
typically use a different type of lubricant than fan shaft
bearings.