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6. Electrical connection
Electrical connection must be carried out by a qualified electrician
in accordance with local regulations.
Observe all national and local regulations relating to safety and
accident prevention.
DANGER
Electric shock
Death or serious personal injury
- Before making any electrical connections, make
sure that the fuses have been removed or the main
switch has been switched to off. Make sure that
the power supply cannot accidentally be switched
on.
The explosion protection classification of the SMD
mixer is Class I, Division 1, Groups C and D, T4. The
classification of the installation must be approved by
the local authorities in each individual case.
FM
For the electrical installation, the standard ANSI/IEC
60079-14 must be met.
The safety instructions in section
versions
must be observed.
The supply voltage and frequency are marked on the mixer or
flowmaker nameplate. Make sure that the mixer or flowmaker is
suitable for the power supply available at the installation site.
The mixer or flowmaker is supplied complete with a power cable.
Standard cable lengths are 33 or 49 ft (10 or 15 m). Longer
cables are available on request. See section
technical
data.
The motor is marked either with a Y, star, or a Δ, delta. For 10-
and 11-wire cables, this connection is to be made in an external
control panel using conductors 1 to 6 of the power cable.
Figure
24
shows a schematic drawing of these star and delta
connections. See also section
6.4 Wiring diagrams for SMG and
SFG.
6.1 Motor protection
Mixers and flowmakers are provided with the following types of
motor protection:
•
Standard mixers incorporate three bimetallic PTO thermal
switches. See fig. 25.
•
Standard flowmakers incorporate three PTC sensors. See fig.
26.
Function of thermal switches
The motor is protected against overheating by three thermal
switches connected in series, one switch in each winding.
When the maximum winding temperature is reached, the switch
will open the circuit and stop the motor.
When the windings have cooled to normal temperature, the
switch closes the circuit and you can restart the motor. Manual
restarting is necessary.
See wiring diagram in fig. 25.
Thermal switches (F6):
•
Two conductors, terminals 11 and 12.
•
Maximum operating voltage: 250 V.
•
Maximum switching current: 2.5 A at cos φ = 1.
3.3 Explosion-proof
•
Cutting-out temperature: SMD: 266 °F (130 °C), SMG and
SFG: 302 °F (150 °C).
Function of PTC sensors
When overheated, the motor stops. Automatic restarting is not
permitted in such cases. This requires a thermistor trigger unit
with a reconnection suppressor in the control circuit of the motor
contactor.
12.1 General
See wiring diagram in fig. 26.
ϑ1, ϑ2, ϑ3: PTC sensors:
•
Two conductors, terminals 31 and 32.
•
Maximum voltage at the terminals: U
•
Resistance between terminals 31 and 32:
– at room temperature R = 150 to 750 Ω
– at cutting-out temperature 266 °F (130 °C) R ≥ 4000 Ω.
FM
max.
The voltage at terminals 31 and 32 must not exceed
2.5 V (AC/DC). Use an ohmmeter for testing the
voltage.
Explosion-proof mixers must be protected against
excess temperature by means of PTC or PTO
(Klixon) sensors. The sensors must be connected to
a certified signal converter with safety level SIL 1. If
the relay is incorporated in a frequency converter, the
converter must also fulfil SIL 1.
= 2.5 V (AC/DC).
15
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