5.2.1 Automatic Motor Adaptation
Automatic motor adaptation (AMA) is an automated test
procedure used to measure the electrical characteristics of
the motor. AMA provides an accurate electronic model of
the motor, allowing the drive to calculate optimal
performance and eciency. Running the AMA procedure
also maximizes the automatic energy optimization feature
of the drive. AMA is performed without the motor rotating
and without uncoupling the load from the motor.
5.2.2 Built-in PID Controller
The built-in proportional, integral, derivative (PID)
controller eliminates the need for auxiliary control devices.
The PID controller maintains constant control of closed-
loop systems where regulated pressure, ow, temperature,
or other system requirements must be maintained.
The drive can use 2 feedback signals from 2 dierent
devices, allowing the system to be regulated with dierent
feedback requirements. The drive makes control decisions
by comparing the 2 signals to optimize system
performance.
5.2.3 Motor Thermal Protection
Motor thermal protection can be provided via:
•
Direct temperature sensing using a
- PTC- or KTY sensor in the motor
windings and connected on a standard
AI or DI.
- PT100 or PT1000 in the motor windings
and motor bearings, connected on VLT
®
Sensor Input Card MCB 114.
-
PTC Thermistor input on VLT
®
PTC
Thermistor Card MCB 112 (ATEX
approved).
•
Mechanical thermal switch (Klixon type) on a DI.
•
Built-in electronic thermal relay (ETR).
ETR calculates motor temperature by measuring current,
frequency, and operating time. The drive shows the
thermal load on the motor in percentage and can issue a
warning at a programmable overload setpoint.
Programmable options at the overload allow the drive to
stop the motor, reduce output, or ignore the condition.
Even at low speeds, the drive meets I2t Class 20 electronic
motor overload standards.
1.21.0 1.4
30
10
20
100
60
40
50
1.81.6 2.0
2000
500
200
400
300
1000
600
t [s]
175ZA052.11
fOUT = 0.2 x f M,N
fOUT = 2 x f M,N
fOUT = 1 x f M,N
IMN
IM
Figure 5.1 ETR Characteristics
The X-axis shows the ratio between I
motor
and I
motor
nominal. The Y-axis shows the time in seconds before the
ETR cuts o and trips the drive. The curves show the
characteristic nominal speed, at twice the nominal speed
and at 0.2 x the nominal speed.
At lower speed, the ETR cuts o at lower heat due to less
cooling of the motor. In that way, the motor is protected
from being overheated even at low speed. The ETR feature
calculates the motor temperature based on actual current
and speed. The calculated temperature is visible as a
readout parameter in parameter 16-18 Motor Thermal.
A special version of the ETR is also available for EX-e
motors in ATEX areas. This function makes it possible to
enter a specic curve to protect the Ex-e motor. See the
programming guide for set-up instructions.
5.2.4 Motor Thermal Protection for Ex-e
Motors
The drive is equipped with an ATEX ETR thermal
monitoring function for operation of Ex-e motors according
to EN-60079-7. When combined with an ATEX approved
PTC monitoring device such as the VLT
®
PTC Thermistor
Card MCB 112 option or an external device, the installation
does not require an individual approval from an
approbated organization.
The ATEX ETR thermal monitoring function enables use of
an Ex-e motor instead of a more expensive, larger, and
heavier Ex-d motor. The function ensures that the drive
limits motor current to prevent overheating.
Product Features Design Guide
MG22B222 Danfoss A/S © 01/2018 All rights reserved. 21
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