Welding Machines for shipboard use

Transcription

1 Welding Machines for shipboard use By Leif Andersen, Technical Product Manager Welding, WSS Every so often, we are asked what the difference is between Unitor welding machines and other brands. In this article, we explain the difference between welding machines for land based and shipboard use both concerning compliance, safety and quality. Historic background Through more than 60 year, Unitor welding machines have been supplied to the maritime industry. The equipment have played a major part in safe and reliable maintenance welding on-board vessels Welding converter Electric motor Generator 1920 Welding transformer Transformer 1950 Welding Rectifier Transformer Diode Inductor 1970 Thyristor controlled Welding Rectifier Transformer Thyristor Inductor 1980 Welding Inverters Diode Transistor Transformer Diode Inductor The Transformers were uncomplicated machines that only brought the high voltage on the mains down to the open circuit voltage plus a simple way of regulating amperage output. The alternating current from the mains still come out as high-risk alternating current. The introduction of the rectifiers meant that not only was the voltage reduced in the transformer part, but also that the current also was converted (rectified) from alternating current to direct current by silicone diodes. The inverter revolution meant a lot when it comes to the weight and size of welding machines. By first converting alternating current at 60Hz from the mains over to direct current for so to chop it up to approximately Hz it was possible to use a small size transformer to bring down the voltage. After that, it was once again rectified to direct current and smoothened out by an inductor. The reduction of the transformer part gave an amazing weight reduction.

2 TR-3/ UWT-300 TRANSFORMER 300 A Weight: 145 Kg UWR-303 RECTIFYER 300 A Weight: 95 Kg UWI-320TP INVERTER 320 A Weight: 18 Kg Note the dramatic weight and size reduction when changing from Rectifier to Inverter technology. A ship at sea depends upon safe and reliable welding equipment to upkeep its operational efficiency. Unitor Electric arc welding power sources are portable or transportable to facilitate maintenance welding taking place on a variety of locations and environments on-board, -from the open deck to double bottom. So what makes the Unitor welding machine range unique for maintenance welding on-board? TP Total Protection Function. The Total Protection (TP) function prevents damage to the machine in the event of the primary voltage is too high or a phase fallout. If a voltage surge from the mains hits a welding machine it will receive fatale damage. If this happens to a Unitor TP machine, it will close itself down and the red diode on the back will light up. The machine will not be possible to re start before the problem on the mains have been corrected. VRD Voltage Reduction Devise The definition of Open Circuit Voltage (OCV) is the voltage between the welding machines terminal when switched ON, but not welded with. It is sometimes referred to as No Load Voltage or Touchable voltage. The VRD gives Open Circuit Voltage OCV (touchable voltage) less than 12V for the entire Unitor machine range. It makes the machines safe to work with and in compliance to rules and regulations. Maritime and Coastguard Agency (MCA), Code of Safe Working Practices for Merchant Seamen specify less than 70V OCV for Direct current welding machines. Australian Standard AS specify DC only and Touchable voltage (arc sensing voltage) max. 35 Volt by the use of Voltage Reduction Devise (VRD).

3 Total protection function All Unitor welding machines conforms to AS Safety in welding and allied processes. Keep in mind that Land based welding machine can have as high as 113 V OCV for DC welding machines and still be inside rules and regulations. For AC welding machines the OCV for land based welding machines can be 48 V ( ). Make sure this type of machines are not found onboard. This is the motor plate on a land based welding machine. It has CE, S, IP 23S so all looks good except for OCV that is far above legal limit for use on-board. CE= Conformity European This confirms that Welding machine is built according to Directives & Standards governed in European Community. EN European Norm for electromagnetic compatibility. EN European Norm for arc welding appliance. This prevents inferior electric equipment being put to use endangering the crew. Welding machines are ruled by the IEC 60974, which is the EN in Europe. This norm is internationally accepted, also in USA. All Unitor machines are manufactured according to IEC / EN

4 S marking This indicates that the welding machine is suitable for use in areas with increased electric shock hazard. Important when work takes place in seawater environment in combination with high humidity and high temperatures and where ship s hull is used as returned conductor. One should of course never use hull as return conductor but this is never the less practised by many welders. Vessels are mostly made of steel. Despite being totally against regulations, the welders often place the return clamp (earth/ ground clamp) to the nearest bulb iron and use the vessel as return. The Return Cable is often referred to as earth or ground. It is neither Earth nor Ground but a Return. There is just as much current running through the Return cable as the Welding cable. The welding/return cable is part of an electric circuit. If the Return clamp is placed to the nearest bulkhead next to the welding machine the ship hull becomes live. The welder in worst case can be electrocuted if in contact with the current flow. This will be more likely if the welding machine is a Transformer delivering AC current or a high Open Circuit voltage (OCV). The Return clamp with its cable must be placed as near to where welding takes place as possible. Using the hull as return can also give damage to mechanical components on-board. When an electric current passes through a motor bearing i.e. proceeds from one ring to the other via the rolling elements, damage will occur at the contact surfaces. The process is similar to electric arc welding. (Maritime and Coastguard Agency Code of Safe Working Practices for Merchant Seamen specify, Use of the hull as return conductor is against regulations ). Ingress Protection IP23 This informs the Unitor machines protection against objects and liquids Unitor welding machines are according to IP23 reg. Protection degree of the casing according to EN First didget 2 informs Protection against object not greater than 80mm in length and 12mm in diameter Second didget 3 informs Protection from sprayed water at an angle of 60º from vertical The Thermal insulation class All Unitor welding machines are H class. This is the highest class for welding machines and informs that the main transformers insulation material and insulation system can take up to 180 C. RoHS2 All Unitor Welding Machines conform to RoHS2 directive that restricts the use of specific hazardous or restricted substances in new electrical and electronic equipment put on the market in the European Union after July 1, On July 1, 2011, the European Union Published the RoHS2 (Recast Directive). The restricted substances are: Lead (0.1%) Mercury (0.1%) Cadmium (0.01%) Hexavalent chromium (0.1%) Polybrominated biphenyls (0.1%) Polybrominated diphenyl ethers (PBDE) (0.1%) Polybrominated biphenyls and Polybrominated diphenyl ethers are both flame retardant products used as cable insulation. Non-asbestos declaration This confirms further that no asbestos is used in the Unitor welding machines. Heavy metals and Asbestos will be a health hazard to the operator and environment.

5 A welding range in compliance with rules and regulations, safety and quality UWI-150 TP 1 phase 230V 150 Amp Electrode &TIG DC UWW-161TP 1 phase 230V 150 Amp Electrode &TIG DC Wire Welding UWI-230TP AC/DC 1 phase 230V 200 Amp Electrode &TIG AC/DC UWI-203TP 3 phase V 200 Amp Electrode & TIG DC UWI-320TP 3 phase V 320 Amp Electrode & TIG DC UWI-500TP 3 phase V 500 Amp Electrode & TIG DC ACA Gouging, Wire Welding UWF-102 Wire Feeder for UWI-500TP The Unitor welding machines fit the Unitor range of transport trolley and skid options. Note that Unitor transport trolleys comes with a TuV lifting certificate. The trolley is tested and certified according to the international labour office for testing and examination of lifting gear used in loading and unloading of ships. The skid trolley is primarily for fast and efficient transportation from location to location. It also gives good protection against mechanical damage.

6 Fast recap: Total Protection (TP) function that protects the welding machine against voltage surges: Protects the machine from damage and keep it operational Voltage Reduction Devise (VRD) keep open Circuit Voltage at max 12V: Protects the welder against electric shock CE= Conformity European is informing that the Welding machine is built according to Directives & Standards governed in European Community. S marking indicates that the welding machine is suitable for use in areas with increased electric shock hazard Ingress Protection IP23 states the Unitor machines ability to protect against objects and liquid. The Thermal insulation class of all Unitor welding machines are H indicating that the main transformers insulation material and insulation system can take up to 180 C. All Unitor Welding Machines conform to RoHS2 directive that restricts the use of specific hazardous or restricted substances. A non-asbestos declaration confirms that no asbestos is used in the Unitor welding machines. On to the mentioned benefits, also add: All Unitor welding machines can do TIG welding thereby extending the machines maintenance capability to also repair seawater pipes made of Copper Nickel and Aluminium bronze and thin plate stainless steel. In TIG mode the machine is fitted with Lift Arc TIG start so there will be no High Frequency disturbing radio communication on-board.