Grundfos S Series User Manual

5.5.1 Thermal switches
The thermal protection against overheating is
achieved with 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.
The switching current for the thermal switch is 0.5 A
at cos φ 0.6.
The thermal protection of the explosion-
proof pumps must not restart the pump au-
tomatically.
Install an automatic circuit breaker, which
disconnects the power supply in case the
thermal- or moisture switches are not op-
erating.
5.5.2 Moisture switches
Non-explosion-proof pumps have one moisture switch
fitted in the chamber.
Ranges 50-58 and 70 explosion-proof pumps have
two moisture switches: one below the motor top cover
and one in the stator housing.
Range 62 pumps have 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.
5.5.3
Pt100
The Pt100 temperature sensor is available as an
accessory or as a Factory Product Variant (FPV).
The Pt100 sensor is primarily used for the monitoring
of the bearing temperature, but it can also be used in
the stator.
If the pump does not have an SM 113, remove the
Pt100 sensor and connect it to an external unit. See
fig. Sensor connections, SM 113 outside the motor. If
the pump has an SM 113, connect the Pt100 sensor
to it. No external unit is required.
For range 50-54 explosion-proof pumps,
the temperature sensor is only available
for monitoring the lower bearing tempera-
ture.
For range 58-70 explosion-proof pumps,
the temperature sensor is available for
monitoring both the lower and the upper
bearing temperatures.
The maximum alarm temperatures are listed below:
Pump
range
Alarm temperatures
Winding tem-
perature
[°C]
Upper
bearing
[°C]
Lower
bearing
[°C]
50-54 150 130 90
58-70 150 120 100
Related information
5.5 Switches and sensors
5.5.4 Thermistors
Thermistors are available as an accessory or as an
FPV.
The thermistors can be used as motor protection
devices to monitor stator temperature instead of
thermal switches and must be connected to the
thermistor relay in the control cabinet.
27
English (GB)

Grundfos S Series Specifications

General

Brand	Grundfos
Model	S Series
Category	Water Pump
Language	English