Danfoss VLT AutomationDrive FC 302 Design Manual page 23

Product Features
exceeding the maximum allowable
voltage at motor terminals.
-
Minimum switching frequency of the
drive does not meet the requirement
stated by the motor manufacturer. The
minimum switching frequency of the
drive is shown as the default value in
parameter 14-01 Switching Frequency.
Compatibility of motor and drive
For motors certified according to EN-60079-7, a data list
including limits and rules is supplied by the motor
manufacturer as a data sheet, or on the motor nameplate.
During planning, installation, commissioning, operation,
and service, follow the limits and rules supplied by the
manufacturer for:
•
Minimum switching frequency.
•
Maximum current.
•
Minimum motor frequency.
•
Maximum motor frequency.
Illustration 5.2 shows where the requirements are indicated
on the motor nameplate.
When matching drive and motor, Danfoss specifies the
following extra requirements to ensure adequate motor
thermal protection:
•
Do not exceed the maximum allowed ratio
between drive size and motor size. The typical
≤2xI
value is I
VLT, n m,n
•
Consider all voltage drops from drive to motor. If
the motor runs with lower voltage than listed in
the U/f characteristics, current can increase,
triggering an alarm.
MG38C202
Design Guide
CONVERTER SUPPLY
VALID FOR 380 - 415V FWP 50Hz
3 ~ Motor
1
MIN. SWITCHING FREQ. FOR PWM CONV. 3kHz
2
l = 1.5XI
3
MIN. FREQ. 5Hz
4
f [Hz]
PTC
1 Minimum switching frequency
2 Maximum current
3 Minimum motor frequency
4 Maximum motor frequency
Illustration 5.2 Motor Nameplate showing Drive Requirements
For further information, see the application example in
chapter 12 Application Examples.
5.2.5 Mains Drop-out
During a mains drop-out, the drive keeps running until the
DC-link voltage drops below the minimum stop level. The
minimum stop level is typically 15% below the lowest
rated supply voltage. The mains voltage before the drop-
out and the motor load determines how long it takes for
the drive to coast.
The drive can be configured (parameter 14-10 Mains Failure)
to different types of behavior during mains drop-out:
•
•
•
•
Flying start
This selection makes it possible to catch a motor that is
spinning freely due to a mains drop-out. This option is
relevant for centrifuges and fans.
Kinetic back-up
This selection ensures that the drive runs as long as there
is energy in the system. For short mains drop-out, the
operation is restored after mains return, without bringing
Danfoss A/S © 01/2018 All rights reserved.
1180 x
t = 10s t = 10min
OL COOL
M,N
MAX. FREQ. 85 Hz
PWM-CONTROL
5 15 25
Ix/I 0.4 0.8 1.0
M,N
°C DIN 44081/-82
EN 60079-0
Manufacture xx
EN 60079-7
Trip lock once the DC link is exhausted.
Coast with flying start whenever mains return
(parameter 1-73 Flying Start).
Kinetic back-up.
Controlled ramp down.
Ex-e ll T3
5
50 85
1.0 0.95
21
5