Xylem FLYFT P7900, Installation, Operation And Maintenance Manual

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• Early warning: “B”-alarm
• Pump stop: “A”-alarm
3.4.4 Stator temperature monitoring methods
The purpose of stator winding temperature monitoring is to make the motor shut off at high
temperature. There are several monitoring methods, depending on the voltage of the motor,
and types of thermal sensors chosen.
By using an analogue sensor, two adjustable alarm limits can be used, one for warning (“B”-
alarm) and one for pump stop (“A”-alarm). The configurations which can be used for
monitoring the stator winding temperature depend upon the voltage range of the drive unit.
See
Drive units
on page 10 for the voltage range for each drive unit.
Up to 1 kV drive units
Table 1: Stator temperature monitoring configuration, up to 1 kV
Standard / Optional Monitoring configuration description
Standard
• Three thermal contacts, connected in series, are incorporated in the coil ends
of the stator winding. The contacts are normally closed, and open at 140°C
(285°F).
• One Pt100 sensor is incorporated in one of the windings.
Or:
• Three thermistors, PTC, connected in series, are incorporated in the coil ends
of the stator windings. T
Ref
=140°C (285°F).
• One Pt100 sensor is incorporated in one of the windings.
Optional • Three thermal contacts, connected in series, are incorporated in the coil ends
of the stator winding. The contacts are normally closed, and open at 140°C
(285°F).
• Three Pt100 sensors, one for each phase, are incorporated in the windings.
Or:
• Three thermistors, PTC, connected in series, are incorporated in the coil ends
of the stator windings. T
Ref
=140°C (285°F).
• Three Pt100 sensors, one for each phase, are incorporated in the windings.
3.4.4.1 Temperature sensors
Table 2: Thermal contact
Description Measured value Fault values
The thermal
contact is a
normally closed
contact.
0–3 ohm, unless the wires are long. An infinite value (open circuit) indicates
either high temperature or a fault.
Examples of faults include a broken wire,
or a bad contact in a connector.
Table 3: PTC thermistor
Description Measured value Fault values
The PTC
thermistor is a
semiconductor
device.
Resistance at normal temperature:
• 50–100 ohm (150–300 ohm for three in
series).
• Above the tripping point, T
Ref
, the
resistance increases dramatically to
several kilohm.
• An infinite value (open circuit)
indicates a fault. Examples of faults
include a broken wire, or a bad
contact in a connector.
• A value close to zero indicates a short
circuit in the wiring.
3 Product Description
12 P7900 Installation, Operation, and Maintenance Manual