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6.5 Switches and sensors
Do not let the pump run dry.
Install an additional level switch to ensure that the pump is stopped
in case the primary stop level switch is not operating.
A pump includes the following switches and sensors:
•
three thermal switches or three thermal protectors in the stator
windings
•
moisture switches:
- in range 50-70: one under the motor top cover
- in Ex-pumps, range 50-58 and 66-70: one under the motor
top cover and one in the stator housing
- in Ex pump, range 62: two under the motor top cover.
•
one optional Pt100 sensor in the bearing or in the stator winding
•
one analog and optional WIO sensor in the oil chamber.
1
8
Sensor cable
Pos.
Description
1
Yellow and green
Sensor connections, SM 113 outside the motor
3
9
1
4
2
7
5
6
Symbol
Description
A
Power side
B
Signal side
WIO sensor
WIO
"mb" approval
C
"d" enclosure
T
Thermal switch
M
Moisture switch
P
Power input
S
Sensor input
SM 113
Sensor board
IO 113
IO 113 with internal alarm relay (250 VAC)
"d"
Flameproof enclosure
"mb"
Protection according to EN/IEC 60079-18:2004
6.5.1 Thermal switches
The thermal protection against overheating is ensured through
bimetallic switches as standard or thermistors as optional.
The three thermal switches that are hardwired from the pump to IO
113, or a similar controller, open if the stator windings become
overheated. The thermal switches are reversible and close again
when the motor is cooled down.
This generates both a hardware and a software alarm in IO 113,
and the alarm relay opens.
Install an automatic circuit breaker, which disconnects the
power supply in case the thermal switches or the moisture
switches are not operating.
Maximum switching current for the thermal switch is 0,5 A
at cos φ 0.6.
6.5.2 Moisture switches
Non-explosion-proof pumps have one moisture switch which is
fitted in the chamber below the motor top cover.
Ranges 50-58 and 66-70 explosion-proof pumps have two moisture
switches, one below the motor top cover and one in the stator
housing in the bottom of the motor.
Range 62 has both moisture switches placed below the motor top
cover.
The moisture switches are hardwired from the pump to IO 113, or a
similar controller. They open if moisture is detected and break an
electric circuit. This generates both a hardware and a software
alarm in IO 113, and the alarm relay opens.
The switching current on the moisture switch is 6 A.
23
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