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Melitta LOOK User Manual

Melitta LOOK
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14
4.5 Functional testing
Equipment required (all versions):
Variac transformer
DC voltmeter to check nominal dc volts
AC voltmeter to cover setting range
Resistance meter
AC ammeter 0-10mA
One double pole switch
One electronic timer
MVTU 11 and MVTU 12 380/440V versions only:
Step-up transformer to cover setting range of 380/440V relay
MVTU 13 and MVTU 18:
One 6W 50k wirewound resistor
Note: Measuring accuracy depends on the accuracy of the instruments used.
4.5.1 DC auxiliary supply check
Ensure that the correct series dropping resistor(s) are fitted if required. Remove the
relay from its case and check that the incoming dc supply at the relay case terminal
13(+ve) and 14(–ve) is within the range specified below:
Rated dc voltage (V) DC operative range (V)
30/34 24 37.5
48/54 37.5 66
110/125 87.5 150
220/250 175 300
4.5.2 Test block type MMLG
If a test block is included in the scheme, it may also be associated with protection CT
circuits. It is important that the sockets in the type MMLB01 test plug, which
correspond to the current transformer secondary windings, are LINKED BEFORE THE
TEST PLUG IS INSERTED INTO THE TEST BLOCK
DANGER: DO NOT OPEN CIRCUIT THE SECONDARY CIRCUIT OF A
CURRENT TRANSFORMER SINCE THE HIGH VOLTAGE
PRODUCED MAY BE LETHAL AND COULD DAMAGE
INSULATION.
The test plug isolates terminals 13 & 14, removing the dc positive, making it
necessary to add a link between these terminals on the test plug to restore the
auxiliary supply to the relay.
4.5.3 Isolation of VT circuit
Before any secondary injection tests are carried out, the voltage transformer supply to
the relay should be isolated by means of the panel links or connecting blocks.

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Melitta LOOK Specifications

General IconGeneral
TypeFilter Coffee Machine
Capacity10 cups
Keep Warm FunctionYes
ProgrammableNo
Coffee TypeGround coffee
Water Level IndicatorYes
Water TankRemovable
Water Tank Capacity1.25 L
Automatic Shut-OffYes

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