Zenit UNIQA Serie Manual De Instalacion Y Uso página 44

Safety, Installation and Operations Manual – Translation of original instructions
4.11 Installing the float switch control system (Fig. 11)
Float switches allow one or more pumps to be started and stopped in response to the level of liquid in the tank.
They can also be connected to alarm devices to prevent operational problems (overflow or dry running).
They must be installed well away from turbulence or inflows of water.
In the event of strong turbulence, float switches should be installed on a rigid rod mounted inside the pit.
Make sure that there are no items which may obstruct movement of the floats and that the wires do not interfere
with each other, and cannot become tangled or trapped on projections inside the tank.
Float switches must be installed in such a way that the correct minimum liquid level is guaranteed.
The user must ensure that the pump operates always with the minimum level of pumped liquid
controlled by two level sensors (in redondancy) to shut down the power supply when the liquid to
be pumped belows the minimum level.
Only use level sensor according with the -Ex classification of the installation site.
The connection to the electric control panel must be carried out using an Intrinsic Safe Circuit such
as a Zener safety barrier or a galvanic isolation barrier.
Minimum liquid level
WET version: fully submerged pump (Fig. A2). The liquid in the tank must never drop below the motor cover in order to ensure
that the pump is cooled effectively.
EN
DRY version: fully submerged pump body (Fig. B2) or filled pump body (Figs. C2 - D2).
caution
Always check to ensure that the pump is operating with the correct minimum level of liquid. Depending on the specific
installation, additional measures may be necessary to ensure that turbulence does not cause an inflow of air into the suction port.
Ensure that the switch from shut down to start-up
occurs only and exclusively if the floats find themselves in the position shown in Fig. 12 A - B - C - D.
Ensure that the switch from start-up to shut down
occurs only and exclusively if the floats find themselves in the position shown in Fig. 13 A - B - C - D.
The electric connection of the floats must be carried out in such a way that ensures the shutdown of the pump in cases of a
malfunctioning float.
Make sure that effective volume of the tank does not become so low that the number of starts per hour exceeds the maximum
admitted.
ON
12 A
OFF
13 A
44
ON
12 B
OFF
13 B
ON
12 C
OFF
13 C
better together
ON
OFF
11
ON
12 D
OFF
13 D