Mitsubishi Electric PUZ-WZ50VAA Service Manual page 8

• Keep ignition sources away from outdoor units containing R290 refrigerant. Even in a well ventilated environment, do
not bring ignition sources into the Protected Zone described in section 2.7.
• Do not smoke during work and transportation.
(1-7) Ventilated Area
Ensure that the area is in the open or that it is adequately ventilated before breaking into the system or conducting any
hot work. A degree of ventilation shall continue during the period that the work is carried out. The ventilation should
safely disperse any released refrigerant and preferably expel it externally into the atmosphere.
Do not install the unit and work in places where refrigerant may build-up or places with poor ventilation such as a semi-
basement.
When performing the work in a closed room, small room, or similar location, provide adequate ventilation due to open
the doors or windows and using a fan compliant with R290.
(1-8) Checks on the Refrigeration Equipment
Where electrical components are being changed, they shall be fit for the purpose and to the correct specification. At all
times the manufacturer's maintenance and service guidelines shall be followed. If in doubt, consult the manufacturer's
technical department for assistance.
The following checks shall be applied to installations using flammable refrigerants:
• The charge size is in accordance with the room size within which the refrigerant containing parts are installed.
• The ventilation machinery and outlets are operating adequately and are not obstructed.
• Marking to the equipment continues to be visible and legible. Markings and signs that are illegible shall be corrected.
• Refrigeration pipe or components are installed in a position where they are unlikely to be exposed to any substance
which may corrode refrigerant containing components, unless the components are constructed of materials which are
inherently resistant to being corroded or are suitably protected against being corroded.
• The secondary circuit (heating/cooling circuit) shall be checked for the presence of refrigerant.
(1-9) Checks on Electrical Devices
Repair and maintenance to electrical components shall include initial safety checks and component inspection proce-
dures. If a fault exists that could compromise safety, then no electrical supply shall be connected to the circuit until it is
satisfactorily dealt with. If the fault cannot be corrected immediately but it is necessary to continue operation, an ade-
quate temporary solution shall be used. This shall be reported to the owner of the equipment so all parties are advised.
Initial safety checks shall include that:
• capacitors are discharged: this shall be done in a safe manner to avoid possibility of sparking;
- Make sure that LED on the outdoor controller circuit board goes out and wait for at least 1 minute.
- If there is a refrigerant leak, never touch the electrical components while leak detection is being carried out because
spark may occur even if LED1 goes out.
• no live electrical components and wiring are exposed while charging, recovering or purging the system;
• there is continuity of earth bonding
(2) Repairs to Sealed Components
(2-1) During repairs to sealed components, all electrical supplies shall be disconnected from the equipment being worked
upon prior to any removal of sealed covers, etc.
If it is absolutely necessary to have an electrical supply to equipment during servicing, then a permanently operating
form of leak detection shall be located at the most critical point to warn of a potentially hazardous situation.
Locate the detector close to sealed components and avoid concentration of R290 refrigerant around the sealed compo-
nents by using a fan compliant with R290. If it detects a leak, immediately install the sealed cover and leave the area.
(2-2) Particular attention shall be paid to the following to ensure that by working on electrical components, the casing is not
altered in such a way that the level of protection is affected. This shall include damage to cables, excessive number of
connections, terminals not made to original specification, damage to seals, incorrect fitting of glands, etc.
Ensure that the apparatus is mounted securely.
Ensure that seals or sealing materials have not degraded to the point that they no longer serve the purpose of prevent-
ing the ingress of flammable atmospheres. If the sealing materials are degraded or damaged, replace it with a new one.
Replacement parts shall be in accordance with the manufacturer's specifications.
(3) Repair to intrinsically Safe Components
Do not apply any permanent inductive or capacitance loads to the circuit without ensuring that this will not exceed the
permissible voltage and current permitted for the equipment in use.
Intrinsically safe components are the only types that can be worked on while live in the presence of a flammable atmos-
phere. The test apparatus shall be at the correct rating.
Replace components only with parts specified by the manufacturer. Other parts may result in the ignition of refrigerant in
the atmosphere from a leak.
(4) Cabling
Check that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges or any other adverse
environmental effects. The check shall also take into account the effects of aging or continual vibration from sources such
as compressors or pumps.
Use only specified cables for wiring. The wiring connections must be made securely with no tension applied on the termi-
nal connections. Also, never splice the cables for wiring (unless otherwise indicated in the Installation Manual).Failure to
observe these instructions may result in overheating or a fire.
If the supply cord is damaged, it must be replaced by the manufacturer, its service agent or similarly qualified persons in
order to avoid hazard.
OCH816
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