Xylem 7030.090, Инструкция по установке, эксплуатации и обслуживанию

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3.5.4 Bearing temperature measurement
Pt100 sensors monitor the bearing temperatures to protect the pump from the consequences
of a bearing failure.
Main bearing
Main bearing temperature monitoring is standard in the MAS 711 and MAS 801.
Support bearing
Support bearing temperature monitoring is an option in the MAS 711 and MAS 801.
Alarms
Two adjustable alarm limits can be used:
• Early warning: “B”-alarm
• Pump stop: “A”-alarm
3.5.5 Stator temperature monitoring methods
The purpose of stator-winding temperature monitoring is to make the motor shut off at high
temperature. There are two monitoring methods, depending on the types of thermal sensors
chosen.
Table 1: Stator temperature monitoring configuration
Configuration with thermal switches Configuration with thermistors
• Three thermal switches, connected in series, are
incorporated in the coil ends of the stator
winding. The switches are normally closed, and
open at 140°C (285°F).
• One Pt100 sensor is incorporated in one of the
windings.
• 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.
By using an analogue sensor, two adjustable alarm limits can be used, one for warning (“B”-
alarm) and one for pump stop (“A”-alarm).
3.5.5.1 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
16 P7030, P7035, P7040 Installation, Operation, and Maintenance Manual