MERKLE E 420 DC Operation Manual

Operation Manual

MMA/Stick Elektrode Unit

Model E 420 DC

MERKLE
Schweißanlagen-Technik GmbH
Industriestraße 3
D-89359 Kötz
Tel.: [phone]
Fax: [phone]
www.merkle.de

Inhalt Seite

1 Accident prevention regulations 2

1.1 Safety instructions 2

2 Duty cycle 4

3 Instructions to avoid interferences due to electromagnetic influences EMC 4

4 Technical Data 6

4.1

MMA/Stick Electrode Welding Unit Model E 420 DC 6

5 Start Up 7

5.1 Installation of the Machine 7

5.2

Main Supply 7

5.3 Connection of the welding cables 7

5.4 Earth Lead (Work Cable) 8

5.5 Operation mode: TIG 8

5.6 Operation with the unit connected to a generator 8

5.7 Cable prolongations 8

5.8 Transport 8

6 Generalities of the welding unit Model E 420 DC 8

6.1 Cooling of the power modul 9

6.2 Electronics 9

6.3 Electrode Holder 9

6.4 TEDAC-System 9

7 Current Adjusting 9

8 Operation of the unit E 420 DC 11

9 Cleaning 12

10 Maintenance and Accident Prevention 12

11 Trouble Shooting 12

12 Partlist and wiring diagram 14

12.1 Partlist E 420 DC 14

12.2 Wiring diagram E 420 DC 15

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Dear customer,

we wish to thank you for choosing a MERKLE welding machine. In doing so, you have
demonstrated to us the trust you place in our products.

With best wishes

MERKLE
Schweißanlagen Technik GmbH

1 Accident prevention regulations

The following accident prevention regulation is applied for welding with MMA welding
units, type E 420 DC:
VBG 15 / BGV D1* Welding, cutting and allied processes.
A copy of this regulation should be readily accessible in every welding shop. The stipulations
of this regulation are to be observed in the interests of safe and correct welding operation.

Available from the trade association responsible or
Carl Heymanns-Verlag, Luxemburger Strasse 449, 50939 Cologne.

1.1 Safety instructions

This unit is manufactured according to the requirements and stipulations of EN 60974.1 /
VDE 0544. The accident prevention regulations “Welding, cutting and allied processes”
(VBG 15 / BGV D1) of the trade association for precision engineering and electrical
engineering are as well valid.

1) In case of an accident, the welding unit must be disconnected from the mains
immediately.

2) If electrical contact voltages arise, switch off the unit immediately, disconnect it from
the mains and proceed to inspection by a qualified electrician or by our Service
Department.

3) Before opening the unit, disconnect it from the mains supply.

4) Repair work may only be carried out by a skilled electrician or by our Service
Department.

5) Before the unit is put to operation, check it visually, as well as the torch and all cables
and connectors regarding possible external damages.

6) Personal protective equipment in accordance with DIN EN 175, DIN EN 379 and

DIN EN 169.

During the work, the welder’s body must be completely protected against radiation
and burns by means of protective clothing and face protection. Long gloves, aprons
and welding shields with welding filters conforming to DIN EN 470-1 and BGR 189

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must be worn. Synthetic clothing are excluded. Shoes must be closed, not opened (due
to spatters). If necessary, protective headwear must be worn (e.g. for overhead
welding). If cover glasses are used, these must be in accordance with the norms
specified above. As additional protection for the eyes against UV radiation, safety
goggles with side shields and corresponding face protection in accordance with
BGR 192 and BGI 553 must be worn.
Accident prevention regulation BGV D1 § 27 stipulates that it is the responsibility of
the employer to provide suitable personal protective equipment, while § 28 stipulates
that it is the responsibility of the insured to wear suitable clothing.

7) Protection when welding under increased electrical risks
Welding rectifiers and welding power sources which can optionally be used for either
direct or alternating current must be marked "S" in accordance with EN 60974-1 and
BGI 534.
Use insulating materials to protect you against contact with electrically conductive
parts and damp floors. Wear dry, undamaged work clothing, long gloves and footwear
with rubber soles. Ventilate rooms, install extraction systems if required, and wear
respiratory protective equipment if necessary (see Procedural instructions BGV D1

§ 27 and BGI 533, Section 5).

8) In order to prevent stray currents and the effects thereof (e.g. destruction of electrical

protective ground conductors), the welding return cable (workpiece cable) must be
connected directly to the workpiece to be welded or to the table (e.g. welding table,
grid-type welding table, workbench) supporting the workpiece (see BGV D1 § 20).
When installing the ground connection, assure that there is a good electrical contact
(remove rust, paint, etc.).

9) During welding pauses, the welding torch is to be laid down on an insulated surface or
hung up in such a way that it is not in contact with the workpiece and its support
connected to the welding power source (see § 20 BGV D1).
In the case of longer work pauses, the welding unit must be switched off and the gas
cylinder valve must be closed.

10) The shielding gas cylinder must always be protected against tumbling downing using a
safety chain.

11) Under no circumstances the unit may be put into operation while it is opened

(e.g. for repair work). Apart from the safety regulations, sufficient cooling of the
electrical components provided by the fan cannot be guaranteed.

12) In accordance with BGV D1 § 5, people in the vicinity of the arc must also be
informed of the hazards and protected against them. Safety partitions (“welding safety
curtains”) must be erected in accordance with DIN EN 1598.

13) No welding work may be carried out on containers in which gases, fuels, mineral oils
or similar substances have been stored even if they have been empty for a long
time (risk of explosion). See § 31 of accident prevention regulation BGV D1.

14) Welds which will be subjected to high loads and which need to meet specific safety
requirements may only be carried out by specially trained and qualified welders.

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15) Never bring the torch close to your face.

16) In areas at particularly high risk of fire, the welder must obtain a welding permit and
have this on his person throughout the duration of the welding work. On completion of
welding, a fire-guard must be delegated to ensure fire protection.

17) Ventilation measures must be applied in accordance with BGI 553, Section 9.

18) The hazard to eyesight must be indicated by means of a sign at the work site

"CAUTION! Do not look into the arc!".

2 Duty cycle

The duty cylce measurings have been carried out in accordance with
EN 60974-1 / VDE 0544 (10 min working period).
60% duty cycle means:
After a 6 min. welding period a 4 min welding pause must be respected. The electrical
components are thermally protected against overheating.

3 Instructions to avoid interferences due to electromagnetic influences

EMC

The welding unit has been manufactured in accordance with the requirements of guideline
EN 50199 regarding electromagnetic compatibility. It is nonetheless the responsibility of the
user to ensure that the welding equipment is installed and operated in accordance with the
manufacturer’s instructions. If electromagnetic interference is detected, it is the responsibility
of the user of the welding equipment to find a solution with the technical assistance of the
manufacturer. In some cases, it may be sufficient simply to ground the welding current
circuit. In other cases, it may be necessary to build a complete shield for the welding power
source and workpiece using the input filters. In all cases, electromagnetic interference must be
reduced to avoid any possible malfunctions.

Note:

For safety reasons, the welding current circuit may or may not be grounded. No
modifications may be made to the grounding without the approval of an expert who is able to
determine whether the changes might increase the risk of accidents, e.g. by allowing parallel
welding current return paths which could destroy the ground conductors of other equipment.
Further instructions are contained in TEC 974-XX "Arc welding equipment – installation and
use".

a) Evaluation of the installation site

Before installing the welding equipment, the user must evaluate potential
electromagnetic problems in the vicinity. The following must be taken into
consideration:

 Other power cables, control cables, signal and telecommunication cables above, below

and next to the welding equipment

 Radio and television transmitters and receivers
 Computers and other control devices
 The health of people in the vicinity, e.g. use of heart pacemaker and hearing aids
 Calibration and measuring equipment
 Interference immunity of other devices in the vicinity. The user must ensure the

electromagnetic compatibility of other devices used in the vicinity. This may require
additional safety measures.

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b) Procedures to reduce emitted interference

1) Mains supply

Welding equipment is to be connected to the mains in compliance with the
recommendations of the manufacturer. If interference occurs, it may be necessary to
take additional precautions, e.g. filters for the mains connection. Make sure that the
power cable of welding equipment is installed in a fixed position shielded by means of
a metal conduit or similar. The entire length of the shield must be electrically
connected. The shield must be connected to the welding power source in the way to
obtain a good electrical contact between the metal conduit and the housing of the
welding unit.

2) Maintenance of the welding equipment

Welding equipment must be maintained regularly in accordance with the
recommendations of the manufacturer. All access and service doors and covers must
be closed and fastened securely when the welding equipment is in operation. No
modifications whatsoever may be made to welding equipment with the exception of
modifications and adjustments specified in the manufacturer’s operating instructions.

3) Welding cables

Welding cables should be kept as short as possible and routed close together on or
near the floor.

4) Equipotential bonding

It is advisable to interconnect all metallic parts in and next to the welding equipment.
Metallic parts connected to the workpiece can, however, increase the risk of the
welder receiving an electric shock by touching these metallic parts and the electrode
simultaneously. The welder must be electrically insulated against all these connected
metallic parts.

5) Grounding the workpiece

If the workpiece is not connected to the ground for electrical safety reasons, or due to
the size and position of the workpiece, e.g. steel structure or outer wall of a ship,
grounding the workpiece may in some cases, but not all, reduce emitted interference. It
must be ensured that grounding the workpiece will not increase the risk of accidents
for the user and cannot cause the destruction of other electrical equipment. If
necessary, the grounding of the workpiece must be carried out by means of a direct
connection to the workpiece. In countries where a direct connection is prohibited, the
connection must be made by means of suitable reactors, selected in accordance with
national regulations.

6) Shielding

Selective shielding of other cables and devices in the vicinity can reduce interference
problems. For special applications, it may be worth considering shielding the entire
welding system.

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4 Technical Data

4.1 MMA/Stick Electrode Welding Unit Model E 420 DC

Primary:

Supply: 3 x 400 / 415V
Frequency: 50-60 Hz
Cont. power: 11,8 kVA
Cont. current: 17 A
Max. current: 29 A
Cos phi: 0,9

Secondary:

Open circuit voltage: 80 V
Welding voltage: 20-37 V
Welding current: 5-420 A
Duty cycle 40 % (10 min.) 420 A
Duty cycle 60 % (10 min.) 350 A
Duty cycle 100 % 280 A (40°C)

Protection class: IP 23
Insulation class: H
Cooling: AF
Main switch: 3-phase
Potentiometer: welding current
Potentiometer: arc force
Potentiometer: hotstart time
Potentiometer: hotstart current
Socket: remote control
Operation modes: switch: 6-step:
Stick electrode, positive
Stick electrode, negative
Stick electrode, remote control
Stick electrode, TEDAC
Digital read out: welding current, with Hold function
and with pre-indication
Control lamp: mains ON,
thermic protection,
failure,
Hold
Power source: inverter (IGBT)
Functions: hotstart, antistick,
arc force, TIG liftarc
stabilisation: ± 10 % mains voltage fluctuation
Norm: EN 60974-1 "S" / CE
Socket 70 mm²: workpiece cable
Socket 70 mm²: Electrod cable with holder
Power supply cable: 4 x 4 mm², 5 m long
Weight: 58 kgs
Dimensions l x w x h: 605 x 430 x 630 mm

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