Function And Operation; Maintenance And Service - Grundfos MTP 75 Montage- Und Betriebsanleitung

4. Function and operation

The motor temperature is sent as a high-frequency
signal through the motor supply cable.
The limit value has been factory-set to 75°C and
cannot be changed.
The signal transformer supplied with the MTP 75 re-
ceives the temperature signal and the capacitor en-
sures that the signal is stable and does not disturb
other installations.
Relay function:
Build the contact function of MTP 75 into the motor
controller so that the motor stops when the MTP 75
is activated by a motor temperature above 75°C. The
temperature of 75°C must be exceeded for 5 sec-
onds before the relay switches off the motor.
• When the green indicator light is on, the MTP 75
receives a temperature signal.
• When the red indicator light is on, the MTP 75 has
detected a motor temperature above 75°C.
The relay functions are described in the following
tables:
Relay activated:
Terminal
position
• Electricity supply switched on.
• The relay is always activated
during start-up, whether there is
8 - 9 open
a temperature signal or not.
7 - 9 closed
• The relay will be activated even if
the temperature signal dis-
appears during operation.
Relay deactivated:
Terminal
position
• Too high motor temperature de-
tected (red indicator light is on)
8 - 9 closed
or
7 - 9 open
• electricity supply switched off.
Description
Description
Indicator lights:
Indication
No light: 1. Motor stopped.
2. No electricity supply.
3. Electrical fault during tempera-
ture measuring.
Green • There is a temperature signal.
light:
• Motor running.
• Motor temperature ok, i.e. below
75°C.
No green • No temperature signal
light: (temperature signal during opera-
tion only).
• Check why there is no temperature
signal.
• Correct the fault.
Red light: • Motor stopped.
• Motor temperature too high, i.e.
above 75°C for more than 5 sec-
onds.
No red • Motor running.
light:
• Motor temperature below 75°C.
4.1 Signal fault
If the electricity supply has been switched on and the
green and red indicator lights are on at the same
time,
• the MTP 75 does not control the motor via termi-
nals 7 and 9
or
• the MTP 75 has received a "foreign" temperature
signal.
If the capacitor and the signal transmitter have not
been fitted correctly, the cause of the problem may
be "false" signals.
Equipment such as voltage supplies, welding ma-
chines and frequency converters can also send sig-
nals which may disturb the temperature signal that
the MTP 75 is supposed to receive and cause mal-
function.
Fault indication (red indicator light is on):
The MTP 75 can be reset by pressing the reset but-
ton on the front plate or by switching off the electric-
ity supply to the MTP 75.
The MTP 75 has no separate alarm output, but termi-
nal 8 in fig. 1 can be used.

5. Maintenance and service

The MTP 75 requires no maintenance. In case of
fault, the MTP 75 must be replaced by a new one.
Description
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