FX 740 T
page 4 di 7 File: FX740T_r0eng - Ottobre 2004 - Manuale per: FX 740 T
FX 740 T
File: FX740T_r0eng - Ottobre 2004 - Manuale per: FX 740 T page 5 di 7
Connection Instructions
I) The power supply unit must necessarily be earthed by
means of the input earth terminal (the rst one on your left
looking from the terminal side) with a 2.5mm ² cable;
II) The head must be connected to the power supply unit by
means of the earth wire on the earth screws of the head and
of the power supply unit; for safety reasons, another earth
wire must be placed on the earth terminal on the head.
III) The connections between the head and the power supply
unit are carried out by means of terminals: do not turn
the power supply on if all the cables are not correctly
connected in their positions.
IV) Apart from the connection cables to the head, the
connections to the START (temporary contact, normally
open), STOP (contact normally closed) button and to the
INTERLOCK chain are required (closed contact to supply
power). If INTERLOCK is not to be used, terminals 17 and
18 can be connected together on terminal board.
NOTE: While it is absolutely compulsory for the START
button to be in temporary contact, the STOP and
INTERLOCK, may be done by a permanent command
(i.e. stopping the power supply when the contact is
open).
V) Install an external switch in order to disconnect the main
power supply, to be used each time maintenance operations
must be carried out on the power supply unit.
VI) The characteristics of the external switch must comply with
the EN 61010-1 standard, it must be installed near the
power supply unit and easily reachable by the user.
VII) In order to carry out the connection to the numbered
terminal board, remove the M320 card from the special
guides; use the yellow extractors present on the card
widening at the same time the hooks blocking the card
present on the guides. Carry out this operation as well
as the reinsertion of the card only when the mains is not
connected.
Failure to comply with these instructions is dangerous for
those who use the equipment, apart from the possibility to
cause equipment breakdowns.
Power-up procedure
Complete the connection correctly before setting at work.
Caution: if the power supply unit is powered without
the provided high-voltage connection between the power
supply unit and the magnetron, it is impossible to start the
continuous power output, but on the outgoing Faston pin
there is a dangerous voltage; DO NOT restore the high-
voltage connection before discharging the capacitor to
earth.
Caution: connect with a direct cable the earth screw
of the head with the earth screw of the power supply
unit. Failure to make this connection may cause
danger of death!
Activate the external switch to power the equipment: the
presence of the mains is indicated by the “POWON” pilot light
on the M320 card. Wait at least 15 seconds for the pre-heating
of the magnetron lament.
Activate the microwave output power by pressing the START
button.
The output of the unit is interrupted when:
1) the STOP key is pressed (opening of the NC circuit of the
stop)
2) the INTERLOCK chain (temporary or permanent opening
of the NC interlock circuit) is opened
3) the safety thermostat (T=132 °C) placed in the high-
voltage transformer TR2 is opened.
4) the safety thermostat (T=100 °C) placed on the Magnetron
is opened.
There are also two other safety mechanisms:
a) the rst one stops the output if the anodic current drops
below the “minimum current” threshold (approx. 40% of
the rated current). For example, this may depend on the
opening of the high-voltage circuit.
b) The second one stops the output if the anodic current
exceeds the “over-current” threshold. (approx. 20% more
than the rated current). For example, this may occur in case
of short-circuit to earth of the high-voltage connection, or
in case of current leakage due to moisture or dust along the
high-voltage path.
