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OM-2065 / Operation and Maintenance Manual
90SB51 / Spec. 7015-3 / Frequency Converter
When an overload condition develops, wherein the load exceeds the unit's power rating by 25%, the
unit will run for approximately 5 minutes before shutting down. For a 50% overload, the unit will turn
off after approximately 10 seconds. In case of a short circuit, the unit will turn off to avoid damage to
its components.
To prevent excessive current through the ground line, current transformer T13 senses ground line
current and constantly sends a signal to the ground protective circuit. When ground line current
exceeds approximately 25% of rated load, the ground protective circuit shuts the machine down.
f. Alarms
Protective devices and alarms are described in detail in the following paragraphs.
3. Orientation
To avoid confusion in the location of components, the control panel of the unit is located at the FRONT
of the unit. LEFT and RIGHT are determined by looking at the unit from the FRONT.
4. Detailed Description
a. Controls and Control Circuits
All control boards are concentrated in the card cage, a portion of which is visible from the front of
the unit through a small window located just beneath the control panel (See 5, Fig. 1) . All control
circuits are solid state and employ CMOS technology for low power consumption and good noise
immunity. There are 13 boards in the card cage (Fig. 5) which are divided into four groups: Alarm
boards (3) ,Control boards (2) , driver boards (6), Power supply (2).
(1) Alarm Cards
The alarm cards monitor a number of sensors and give signals indicating the nature of a fault
when a fault occurs. Faults in the unit are indicated by red lights (LEDs) which may be observed
through a small window in the front door (5, Fig. 1)
Nov 01/90
"H" Inverter Bridge
Figure 4
Chapter 1-1
Page 5
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