Symbol Description
O
Analog and digital outputs
A
Power side
B
Signal side
WIO
WIO sensor, "eb" and "mb" approval
C
"db" 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)
"db"
Flameproof enclosure of the motor sec-
tion
"mb"
WIO sensor protection by enclosure
"eb"
WIO sensor protection by increased
safety
5.5.1 Thermal switches
The thermal protection against overheating is
ensured with bimetallic switches as standard or
thermistors as optional. The three thermal switches
are hardwired from the pump to the IO 113 or a
similar controller. They 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 the IO 113, and the alarm relay opens.
The switching current for the thermal switch is 0,5 A
at cos φ 0.6.
The thermal protection of explosion-proof
pumps must not restart the pump automat-
ically.
Install an automatic circuit breaker, which
disconnects the power supply in case the
thermal- or the moisture switches are not
operating.
5.5.2 Moisture switch
The pumps have two moisture switches, one below
the motor top cover and one in the stator housing.
The moisture switches are irreversible and must be
replaced if activated.
The moisture switches are hardwired from the pump
to the 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
the IO 113, and the alarm relay opens.
The switching current on the moisture switch is 6 A.
5.5.3 Pt100
The pumps are equipped with Pt100 sensors in the
stator windings, in the upper- and the lower bearing
bracket.
Pt100 makes an analog measurement from 0-180 °C.
The value is measured by SM 113 and transferred to
IO 113 through serial communication.
If the pump does not have an SM 113, hardwire the
Pt100 sensors out of the pump and connect them to
an external unit. If the pump has an SM 113, connect
the Pt100 sensors to the SM 113. An external unit is
not required.
The maximum alarm temperatures are indicated in
the table below:
Pump
range
Alarm temperatures
Winding tem-
perature
[°C]
Upper
bearing
[°C]
Lower
bearing
[°C]
72
150
120
100
74
150
120
120
78
150
120
120
5.5.4 WIO sensor
All Ex pumps must be factory-fitted with an
internal WIO sensor.
Lack of oil may cause overheating and
damage to the mechanical shaft seals.
The WIO sensor in the oil chamber trips
the alarm if the oil quality or quantity is in-
sufficient in the oil chamber.
Do not use Shell Ondina X420 oil without
emulsifier detergent in pumps fitted with a
WIO sensor.
The oil chamber is filled with oil acting as lubricant
and coolant for both mechanical seals. The WIO
sensor measures the water content in the oil
chamber:
•
0-20 % water in the oil does not cause a reaction.
•
Water content outside the measuring range
causes a warning.
•
Low oil level causes an alarm. The pump must not
operate while this alarm is on.
26
English (GB)
Содержание ST-55-520
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