Section One - Danfoss VLT Series Service Manual

DESCRIPTION OF
OPERATION
LOGIC SECTION
DATA
ADRESS
RAM EPROM
CONTROL
Refer to the overall schematic in the Appendix.
This manual in not intended to give a detailed description of the unit's operation.
It is intended to provide the reader a general overview of the function of each of
the unit's main assemblies. With this information, the repair technician should
have a better understanding of the unit's operation and therefore aid in the
troubleshooting process.
The VLT is divided primarily into three sections commonly referred to as: logic,
interface, and power.
The control card contains the majority of the logic section. The heart of the control
card is a microprocessor which controls and supervises all functions of the unit's
operation. In addition, a separate PROM contains the parameter sets which
characterize the unit and provide the user with the definable data enabling the
unit to be adjusted to meet the customer's specific application. This definable
data is then stored in an EEPROM which provides security during power-down
and also allows flexibility for future changes as needed. A custom integrated
circuit generates the PWM waveform which is then sent on to the Interface/ILD
Card gate drive circuits.
KEYBOARD
DISPLAY
D
ANALOG
VVC
INPUTS
A
2
POWER
FEEDBACK
POWER
DIGITAL
INPUTS
1
D
ANALOG
OUTPUTS
A
1
DIGITAL
CHANNEL
1
RELAY
Also, part of the logic section is the keyboard/display
mounted on the control card. The keyboard provides
the interface between the digital logic and the human
programmer. The LCD (Liquid Crystal Display) provides
the operator/programmer with menu selection, unit
status and fault diagnostic information. Programming
is accomplished through the use of four of the eight
keys available on the keyboard. The additional four keys
provide various local controls, depending on the type of
unit.
A series of customer terminals are provided for the input
of remote commands such as: Run, Stop and Speed
Reference. Terminals are also provided to
outputs to peripheral devices for the purpose
monitoring and control. Two programmable relay outputs
are also available to interface the unit with other devices.
In addition, the control card is capable of communicating
via a serial link with outside devices such as a personal
computer or a programmable logic controller.
The control card provides two voltages for use from the
customer terminal strip. The 24VDC is used primarily
to control functions such as: Start, Stop and Forward/
Reverse. The 24VDC is provided from a separate section
of the unit's power supply and is delivered to the control
card from the Interface/ILD Card via the two conductor
ribbon cable.

Section One

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