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7. Protection and control functions
7.1 Motor protection devices
The motors have three thermal protectors connected in series
and one moisture switch. Ex pumps have two moisture switches
connected in series. Protectors and switches are connected in
two separate circuits. The thermal protectors are of the reversible
type, and the moisture switches are of the irreversible type. The
thermal protection circuit, conductors 1 and 3, and the moisture
protection circuit, conductors 2 and 3, have separate outputs to
enable separate alarms if the motor is overheated or affected by
moisture.
All other sensor connections are either led out of the motor,
sensor version D, via conductors 4 to 9, or connected to the
sensor board, sensor version B, and led out of the motor via
conductors 4 and 5.
7.2 Pump controller
S pumps can be connected to a separate Grundfos level
controller, which is available as an accessory:
• type LC for one-pump installations
• type LCD for two-pump installations.
Depending on the application, different types of level control
equipment can be used.
The LC controller is fitted with two or three level switches:
Two level switches for start and stop of the pump. The third level
switch, which is optional, is for high-level alarm.
The LCD controller is fitted with three or four level switches:
One level switch for common stop and two for start of the pumps.
The fourth level switch, which is optional, is for high-level alarm.
When installing the level switches, observe the following points:
• To prevent air intake and vibrations in submerged pumps, fit
the stop level switch in such a way that the pump is stopped
before the liquid level is lowered below the top of the pump
housing.
As a principal rule for pumps in dry installation, the lowest stop
level must be at least 20 cm above the opening of the inlet
pipe.
• Install the start level switch in such a way that the pump is
started at the required start level; however, the pump must
always be started before the liquid level reaches the bottom
inlet pipe to the pit.
• If installed, always install the high-level alarm switch about 10
cm above the start level switch; however, alarm must always
be given before the liquid level reaches the inlet pipe to the pit.
7.3 IO 113
IO 113 forms the interface between a Grundfos sewage and
wastewater pump with analog and digital sensors and the pump
controller. The most important sensor data are indicated on the
front panel.
One pump can be connected to an IO 113 module.
Together with the sensors, the IO 113 forms a galvanic separation
between the motor voltage in the pump and the controller
connected.
IO 113 can do the following as standard:
• protect the pump against overheating
• monitor the moisture in the pump
• measure the stator insulation resistance.
See section
7.3.2 Measurement of insulation resistance
• stop the pump in case of alarm
• remotely monitor the pump via RS-485 communication,
Modbus or GENIbus
• control the pump via a frequency converter.
Combined with SM 113, IO 113 can monitor the bearing
temperature and rotor speed when the motor is switched off.
7.3.1 Galvanic separation
Double-insulated sensors for all measurements of high voltages
ensure the electrical safety. Furthermore, there is a galvanic
separation inside the IO 113.
7.3.2 Measurement of insulation resistance
IO 113 measures the insulation resistance between a stator
winding and earth:
• Resistance above 10 megaohm is ok.
• Resistance between 10 and 1 megaohm will cause a warning.
• Resistance below 1 megaohm will cause an alarm.
Do not install the pump controller
in potentially explosive
atmospheres.
Level switches must be according
to IEC/EC 50495, Annex D.
