Page 63 - impiantistica_3_2015
P. 63
Fig. 2 – Adjustable-speed PDS (Power Drive System) main components
average 60%; The main motor characteristics and specialties are
• altitude: max 1000 m a.s.l.; listed in table 1.
• load type / characteristic: centrifugal pump /
the input step-down isolation
quadratic torque; power transformer
• operational speed range: 70∏100%;
• duty cycle: continuous S1. The technical features of the input step-down
isolation power transformer, the secondary
Additional requirements for the adjustable drive windings of which are connected to the variable
system (figure 2) were as follows: frequency converter, are listed in table 2.
• to provide an accurate harmonic analysis, so
the variable frequency
as to meet the applicable IEEE Std 519 and converter
IEC 61000-3-6 requirements for both voltage
and current harmonic distortion by the VFD on The variable frequency converter consists of
network primary side of the input transformer; several main assemblies: front end section, inverter
• to size the power cable connections between section, cooling system and control unit (figure 5).
the VFD and the motor.
The power supply from the medium
The induction motors voltage line by the secondary winding of
a step-down insulation power transformer
Given the specific harsh environment, climate
and installation conditions and to guarantee through a 24 pulse diode rectifier.
performance exceeding contract requirements, On its motor side, the IGBT based inverter
all the motors were designed respecting the
maximum required dimensions and weights section uses a NPC voltage source
and equipped with motor-mounted, self- configuration controlled
ventilated air-to-air coolers, tailor-made rugged by PWM technology
steel frames, additional painting cycles facing
aggressive desert climate, innovative low-noise
sound-proofing arrangements and materials
(figure 3, figure 4).
Fig. 3 – Induction motor CT 900 Y4 type prepared for shipment at the Fig. 4 – Induction motor CT 400 Y4 type at the Termomeccanica Pompe
Nidec ASI facilities facilities, mounted onto the BP skid
Impiantistica Italiana - Maggio-Giugno 2015 61
