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1.6 Motor Requirements
1.6.1 Motor Limits and Rules
For every certified motor with increased safety, the manufacturer supplies a data list including limits and rules. During planning,
installation, commissioning, operation, and service, respect the limits for:
Minimum switching frequency.
Maximum current.
Minimum motor frequency.
Maximum motor frequency.
Furthermore, respect the following:
Do not exceed the maximum allowable ratio between drive size and motor size. The typical value is I
VLT,n
≤2 x I
m,n
.
Consider all voltage drops from the drive to the motor. If the motor is running with lower voltage than listed in the U/f charac-
teristics, current might increase and cause an alarm.
Multi-motor applications are not allowed. Only connect 1 motor to the drive.
1.6.2 Additional Motor Requirements
The Ex eb motor must be approved for operation in hazardous zones (ATEX Zone 1/21, ATEX Zone 2/22) in combination with drives.
The motor must be certified for the particular hazardous zone.
The Ex ec motor must be approved for operation in hazardous zones (ATEX Zone 2/22) in combination with drives. The motor must
be certified for the particular hazardous zone.
N O T I C E
The motor can be placed in Zone 1/21 or 2/22 according to motor approval. The drive must always be installed outside of the
hazardous zone.
Only operate explosion-protected 3-phase motors with drives if the motors are built, tested, approved, and labeled separately
for this mode.
When the usage of the motor and its thermal protective device are approved for drive operation, use the VLT
®
PTC Thermistor
Card MCB 112 for each ignition protection system for all motor types. For motors of Ex eb and Ex ec ignition protection, which
are OEM-approved for drive operation in Ex-hazardous areas, consider and use the requested limitations in the drive's ATEX ETR
thermal monitoring settings.
The necessary parameters and conditions are on the nameplate and in the documentation of the motor. To prevent prohibited
temperatures, the motors are equipped as standard with thermal winding protection, which has to be evaluated by a suitable
device like MCB 112. The motors must not be operated as a group drive.
1.6.3 Approvals and Certifications
Certification number: PTB 14 ATEX 3009
Certificates and declarations of conformity are available. Contact a local Danfoss partner.
1.7 Abbreviations and Conventions
1.7.1 Abbreviations
Abbreviation
Description
ETR
Electronic thermal relay
LCP
Local control panel
AQ267038105120en-000101 / 130R0104 | 9
Danfoss A/S © 2022.08
Introduction
VLT® PTC Thermistor Card MCB 112
Operating Guide
