ABB ACS480, Руководство по оборудованию, Страница: 48 / 180

protection function that protects the motor and switches off the current when necessary.
Depending on a drive parameter value, the function either monitors a calculated temperature
value (based on a motor thermal model) or an actual temperature indication given by motor
temperature sensors.
The motor thermal protection model supports thermal memory retention and speed sensitivity.
The user can tune the thermal model further by feeding in additional motor and load data.
The most common temperature sensors are:
• motor sizes IEC180…225: thermal switch, for example Klixon
• motor sizes IEC200…250 and larger: PTC or Pt100.
See the firmware manual for more information on the motor thermal protection function.
￭ Protecting the motor against overload without thermal model or
temperature sensors
Motor overload protection protects the motor against overload without using motor thermal
model or temperature sensors.
Motor overload protection is required and specified by multiple standards including the US
National Electric Code (NEC), UL 508C and the common UL/IEC 61800-5-1 standard in
conjunction with IEC 60947-4-1. The standards allow for motor overload protection without
external temperature sensors.
The protection feature allows the user to specify the class of operation in the same manner
as the overload relays are specified in standards IEC 60947-4-1 and NEMA ICS 2.
The motor overload protection supports thermal memory retention and speed sensitivity.
For more information, see drive firmware manual.
Implementing a motor temperature sensor connection
WARNING!
IEC 60664 and IEC 61800-5-1 require double or reinforced insulation between
live parts and accessible parts when:
• the accessible parts are not conductive, or
• the accessible parts are conductive, but not connected to the protective earth.
Obey this requirement when you plan the connection of the motor temperature
sensor to the drive.
You have these implementation alternatives:
1. If there is double or reinforced insulation between the sensor and the live parts of the
motor: You can connect the sensor directly to the analog/digital input(s) of the drive.
See the control cable connection instructions.
2. If there is basic insulation between the sensor and the live parts of the motor: You can
connect the sensor to the analog/digital input(s) of the drive. All other circuits connected
to the digital and analog inputs (typically extra-low voltage circuits) must be:
• protected against contact, and
• insulated with basic insulation from other low-voltage circuits. The insulation must
be rated for the same voltage level as the drive main circuit.
Note: Extra-low voltage circuits (for example, 24 V DC) typically do not meet these
requirements.
48 Guidelines for planning the electrical installation