5.3.1 Thermal switches
Three Klixon bimetallic thermal switches are built into
the stator windings. A contact opens in case of
overtemperature(150 °C). The motor insulation class
is class H (180 °C).
The supply voltage to the thermal switches must be
12-24 V DC.
The thermal switches are connected to the control
cable and must be connected to the safety circuit of
the separate pump controller.
Check whether the circuit resistance is maximum 3 Ω
per thermal switch, with a multimeter.
The motor-protective circuit breaker of the
pump controller must include a circuit
which automatically disconnects the power
supply in case the protective circuit is
opened.
In case the thermal switches or the
moisture switches are not working, install
an automatic circuit breaker.
5.3.2 Moisture switches and leakage switches
Non-Ex version:
One moisture switch and one leakage switch are
mounted in a non-Ex pump. The moisture switch is
placed in the top cover and the leakage switch is in
the chamber above the shaft seal. See Appendix, fig.
4.3, section C-C and E-E.
Ex version:
One moisture switch and one leakage switch are
mounted in an Ex pump. The moisture switch is
placed in the top cover and the leakage switch is in
the stator housing. See Appendix, fig. 4.3, section C-
C and D-D.
All switches in both non-Ex and Ex versions are
hardwired from the pump to IO 113. If moisture or a
leakage is detected, they break an electric circuit.
This generates both a hardware and a software alarm
in IO 113, and the alarm relay opens.
Moisture and leakage switches are motor protection
devices, which protect the motor from damage due to
moisture or leakage.The switches are non-reversing
and they must be replaced after they have been
released.
The moisture and leakage switches are connected in
a separate circuit and to the control cable. See
Appendix. They are also to be connected to the
safety circuit of the separate pump controller.
5.3.3
Thermistors
PTC thermistors are available as accessories or
Factory Product Variants (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.
The operating voltage of PTC thermistors is 2.5 - 7.5
V.
Checks after electrical connection
1. Check whether the circuit resistance is below 150
Ω per thermistor, with a multimeter.
2. Check whether the insulation between circuit and
stator housing is outside the range, with a
multimeter.
3. Carry out similar measurements at the end of the
power cable.
Pt1000 temperature sensor
The Pt1000 temperature sensor is available as an
accessory or an FPV.
The Pt1000 sensor is primarily used for the
monitoring of bearing temperature, but it can also be
used in the stator.
In case of overheating caused, the Pt1000 sensor
trips an alarm and disconnects the power supply at a
preset temperature.
The bearing temperature monitoring
system is only available as an option.
The sensor resistance values are the following:
• 1000 Ω at 20 °C
• 1385 Ω at 100 °C
• approximately 1078 Ω at room temperature.
The temperature limits are the following:
• 90 °C: warning for bearing temperature
• 130 °C: pump stop caused by high bearing
temperature
• 150 °C: pump stop caused by high stator
temperature.
In Ex-approved pumps, the maximum
acceptable alarm temperature in the
bearing sensors is 100 °C for the lower
bearing (shaft end) and 120 °C for the
upper bearing.
Checks after electrical connection
1. Check whether the resistance at room
temperature (20 °C) is approximately 1078 Ω, with
a multimeter.
2. Check whether the insulation between the circuit
and the stator housing is outside the range, with a
multimeter.
22
English (GB)
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