Chapter 2 – Overview of the ACS 502/504
2-20 ACS 502 Installation & Start-up Manual
Automatic Bypass
An Automatic Bypass may be added to the Manual Bypass or Manual Bypass
with Service Switch. The Automatic Bypass automatically transfers the motor
to line power when the drive shuts down on a protective trip. If Automatic
Restart is enabled on the drive, the drive will attempt to automatically restart
before the motor transfers to line power. Bypass transfer occurs when the
drive is in a fault condition and will not reset. When an automatic transfer
occurs, the Bypass indicator light illuminates.
Thermal Motor
Overload Relays
The Thermal Motor Overload Relay Options are relays rated 30, 60, 100, or
180 amps in-line with the output power, and 26 amp relay with 500:5 current
transformers for ratings from 180 to 500 amps. These options are standard,
manually resettable, bimetallic motor overload relays with a Class 20 trip
curve. The relays provide thermal motor protection when operating a motor
from the drive. If a Bypass Option is included, the relays also provide thermal
motor protection across the line power. If the overload trips, power is
removed from the motor whether in Normal or Bypass mode. When the drive
has the Bypass option, an external fault indicator is included. This indicator
will illuminate if the overload relay trips. The overload relay is reset by a
pushbutton on the enclosure door.
Thermal Motor Overload Relays have heater elements to determine the trip
level of the overload relay. The heater element type is stamped on the
element. If the overload is not sized properly for the motor, purchase new
heaters of the correct size. See the following tables for heater sizes. Table 2-6
shows heater sizes for the 30, 60, 100, and 180 amp Furnas relays. Table 2-7
is for ratings over 180 amps, which are Square D devices. Your ACS 502 may
have either one or two overload relays, depending upon how many motors the
drive controls.
To Next Page
Loading...
