Daikin Destiny VFD Series, Installation And Maintenance Manual

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Operation Guidelines
www.DaikinApplied.com 45 IM 782-12 • DESTINY AIR HANDLERS
Operating Limits
Do not exceed the operating limits in Table 33 and Table 34 .
A fan wheel that is operated beyond the rpm and temperature
limits shown may suffer permanent distortion or fracture. The
resulting unbalance may cause severe unit vibration.
Table 33: Forward Curved Fan Operating Limits
Forward curved—housed
Dia.,
(in)
7–7 9–9 10–10 12–12
Twin
10"
Twin
12"
Twin
15"
Max.
rpm
2680 2650 2100 1700 2100 1700 1500
Table 34: Backward Inclined Plenum Fan Operating Limits
Backward inclined —plenum
Dia., (in) 9 10 11 12.5 14 16
Max. rpm 2680 2650 2100 1700 2100 1700
Dia., (in) 18 20 22 25 28
Max. rpm 1500 2675 2310 2060 1840
For units with direct drive plenum fans employing variable
frequency drives, use the formula below to calculate the
maximum allowable frequency associated with the maximum
allowable fan speed.
F
max
= 60 Hz × (W
max
/ W
motor
)
F
max
– maximum frequency allowable for particular application
(Hz)
W
max
– maximum fan speed (rpm); refer to fan curves ( Figure
33 through Figure 41 )
W
motor
– nominal motor speed (1800/3600 rpm); refer to motor
nameplate
Fan Vibration Levels
Each unit as shipped is trim balanced to operate smoothly. To
provide satisfactory operation after shipping and installation,
use the accepted industry guidelines for field balancing fans.
Vibration ≤ 0.20 in/sec.
NOTE: Excessive vibration from any cause contributes to
premature fan and motor bearing failure. Monitor
overall vibration levels every six months of operation.
An increase in levels is an indication of potential
trouble.
Vibration Causes
1. Wheel imbalance
a. Dirt or debris on wheel blades
b. Loose setscrews in wheel hub or bearing-to-shaft
c. Wheel distorted from overspeed
2. Bent shaft
3. Drive faulty
a. Variable pitch sheaves—Axial and radial runout of
flanges, uneven groove spacing, out of balance.
Also similar faults in driven sheave.
b. Bad V-belts, lumpy or mismatched, belt tension too
tight or too loose
4. Bad bearings, loose bearing hold-down bolts
5. Motor imbalance
6. Fan section not supported evenly on foundation