Wilo HC 20.1 E3 Series - Page 36

en Maintenance and repair
36 WILO SE 2019-01
9.5.4.1 Test the resistor for the internal
electrodes for terminal room/mo-
tor compartment monitoring
The internal electrodes are switched in parallel. During testing, all the electrodes are
thus measured together.
Measure the resistor of the electrodes with an ohmmeter. The measured value must ap-
proach “infinity”. At values ≤30kOhm, there is water in the terminal room or motor
compartment. Contact customer service!
9.5.4.2 Test the resistor of the temper-
ature sensor
Measure the resistor of the temperature sensors with an ohmmeter. The following
measured values must be complied with:
ƒ PTC sensor (PTC thermistor): Measured value depends on the number of sensors in-
stalled. A PTC sensor has a cold resistance range of 20to 100ohms.
– With three sensors in series, the measured value range is from 60 to 300ohms.
– With four sensors in series, the measured value range is from 80 to 400ohms.
ƒ Pt100 sensor: Pt100 sensors have a resistance value of 100ohms at 0°C (32°F).
Between 0°C (32°F) and 100°C (212°F), the resistance increases by 0.385ohms per
1°C (1.8°F).
At an ambient temperature of 20°C (68°F), the resistance is 107.7ohms.
9.5.4.3 Testing the resistor of the ex-
ternal electrode for sealing cham-
ber control
Measure the resistor of the electrode with an ohmmeter. The measured value must ap-
proach “infinity”. For values ≤30kOhm, if there is water in the oil – change the oil!
9.5.5 Drain the leakage chamber
-
Fig.9: Drain the leakage chamber
- Drain off the leakage
‡ Protective equipment has been put on!
‡ Pump has been dismantled and cleaned (decontaminated if required).
1. Place the pump upright on a firm surface.WARNING!Risk of hands being crushed.
Ensure that the pump cannot fall over or slip away!
2. Place a suitable tank to collect the operating fluid.
3. Unscrew the screw plug slowly (-) but do not unscrew it completely. WARN-
ING!Overpressure in the motor! Stop turning the screw plug further if hissing
or whistling is audible! Wait until the pressure has completely dissipated.
4. After the pressure has dissipated, fully unscrew the screw plug (-) and drain the
operating fluid.
5. Clean the screw plug (-), replace the seal ring and screw it back in. Max. tightening
torque: 8Nm (5.9ft·lb)!
9.5.6 Coolant change
WARNING
Operating fluid under high pressure!
A pressure of several bar can build up in the motor! This pressure escapes when the
screw plugs are opened. If screw plugs are opened without due caution, they can be
ejected at high speed! To avoid injuries, observe the following instructions:
• Adhere to the prescribed sequence of work steps.
• Unscrew the screw plugs slowly, but never unscrew them completely. As soon
as the pressure escapes (audible whistling or hissing of air), stop turning the
screw plug any further!
• When the pressure has completely dissipated, fully unscrew the screw plugs.
• Wear closed safety goggles.