Derating - Danfoss VLT HVAC Drive FC 102 Design Manual

Mechanical Installation Con...
9.5.1 External Ducting and Derating
If more duct work is added externally to the Rittal cabinet,
the pressure drop in the ducting must be calculated using
Illustration 9.5 – Illustration 9.7.
90
80
70
60
50
40
30
20
10
0 0
Illustration 9.5 Derating vs. Pressure Change for E1–E2
Enclosures, 380–480 V Models: P315 and 525–690 V Models:
P450–P500. Airflow: 650 cfm (1105 m
90
9 9
80
70
60
50
40
30
20
10
0
0.2
Illustration 9.6 Derating vs. Pressure Change for E1–E2
Enclosures, 380–480 V Models: P355–P450 and 525–690 V
Models: P560–P630. Airflow: 850 cfm (1445 m
90
80
70
60
50
40
30
20
10
0
25
Illustration 9.7 Derating vs. Pressure Change for Enclosures
F1–F4. Airflow: 580 cfm (985 m
162
VLT
0.1 3.6 9.8 21.5 43.4 76.0 147.1 237.5 278.9
Pressure change
3
/h)
0.6 2.2 5.8 11.4 18.1 30.8 69.5 152.8 210.8
Pressure change
3
50 75 100 125 150 175
Pressure change
3
/h)
Danfoss A/S © 11/2017 All rights reserved.
®
HVAC Drive FC 102

9.6 Derating

Derating is a method used to reduce output current to
avoid tripping the drive when high temperatures are
reached within the enclosure. If certain extreme operating
conditions are expected, a higher-powered drive can be
selected to eliminate the need for derating. This is called
manual derating. Otherwise, the drive automatically
derates the output current to eliminate the excessive heat
generated by extreme conditions.
Manual derating
When the following conditions are present, Danfoss
recommends selecting a drive 1 power size higher (for
example P710 instead of P630):
•
(Pa)
•
•
•
•
•
Automatic derating
If the following operating conditions are found, the drive
automatically changes switching frequency or switching
pattern (PWM to SFAVM) to reduce excessive heat within
the enclosure:
•
(Pa)
•
•
NOTICE
/h)
Automatic derating is different when
parameter 14-55 Output Filter is set to [2] Sine-Wave Filter
Fixed.
200 225
(Pa)
Low-speed – continuous operation at low RPM in
constant torque applications.
Low air pressure – operating at altitudes above
1000 m (3281 ft).
High ambient temperature – operating at
ambient temperatures of 10 °C (50 °F).
High switching frequency.
Long motor cables.
Cables with a large cross-section.
High temperature on the control card or heat
sink.
High motor load or low motor speed.
High DC-link voltage.
MG16C302