Description Of Components - Grundfos Medium UPM Series Data Booklet

Medium UPM

Description of components

Medium UPM pumps are of the canned-rotor type, that
is pump and motor form an integral unit without shaft
seal and with only one gasket for sealing and four
screws for fastening the stator housing to the pump
housing. The bearings are lubricated by the pumped
medium. The focus has been on using eco-friendly
materials as well as on limiting the number of
materials.
Fig. 24 Example, UPML
Motor
The efficiency of the 4-pole, synchronous,
electronically commutated permanent-magnet (ECM/
PM) motor type is considerably higher compared to a
conventional asynchronous squirrel-cage motor.
The PM motor is designed according to the canned-
rotor principle. The design of the mechanical motor
components has mainly focused on these features:
• robustness achieved through efficient protection of
loaded components
• simple design meaning as few components as
possible, each with several functions
• high efficiency due to permanent magnets and low-
friction bearings.
The motor is cooled by the pumped medium which
reduces the sound pressure level to a minimum. Being
software-protected, the pump requires no further motor
protection. The motor/pump and control box have been
tested according to VDE 0700 and meet the
requirements of EN 61800-3 concerning
electromagnetic compatibility.
Stator housing
The die-cast stator housing with four fixing holes
enables condensed water to escape from the pump
through three drain holes, close to the pump housing.
Consequently, one of the drain holes must always
point downwards. See fig. 25.
The housings are electrocoated.
Fig. 25 Drain hole in stator housing
Stator and windings
The UPML, UPMXL pumps have a three-phase stator.
These pumps are designed for pumping very cold
liquids (down to -10 °C). In such applications,
condensation may occur in the stator housing. To
protect the stator, the copper wires are provided with
reinforced insulation.
Fig. 26 Stator
Shaft with rotor
The shaft is made of ceramics. The rotor core is made
of iron lamination and fitted with neodymium
permanent magnets. The rotor is fitted to the shaft with
a pipe and an elastic sleeve. The rotor is encapsulated
in a thin stainless-steel cladding welded to the end
covers and shaft pipe. To avoid precipitation of calcium
in the radial bearings, the shaft has been plunge-
ground at the journals. It has a through-going hole to
ensure good lubrication and cooling of the upper
bearing. Air in the rotor chamber escapes into the
system through the through-going holes of the shaft.
Fig. 27 Shaft with rotor
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