Introduction; Advantages Of Low Voltage Dc Operation; Principles Of Operation - Control Techniques Unidrive Installation Manual

2

Introduction

Before reading this document it is assumed that the user has familiarised themselves
with the Unidrive SP User Guide.
Any Unidrive SP can be configured for Low Voltage DC (LVDC) operation, however
there are differences in the electrical connections and operating voltage range
depending on the frame size of the drive.
This installation guide covers the following:
• Principles and advantages of Low Voltage DC operation
• Safety information
• Detailed information on required external components
• System design
• Electrical Installation
2.1

Advantages of Low Voltage DC operation

Low Voltage DC operation is intended for motor operation in an emergency back-up
situation following failure of the AC supply, for example in elevators, or to limit the motor
speed of servo motors during commissioning of equipment, for example a robot cell.
Even though Low Voltage DC operation is intended for an emergency back-up situation,
it is also possible to run the drive permanently in this mode. In the case were the Low
Voltage DC power supply is in the form of a battery the length of time that the drive will
run is limited by the battery capacity.
2.2

Principles of operation

The Unidrive SP is normally operated from a 3-phase AC supply (200V, 400V etc.) or a
DC supply of the equivalent rectified voltage. This provides power for all control circuits
via the SMPS (Switch Mode Power Supply), and power for the motor via the inverter.
Instead of powering the drive from a 3-phase AC supply it is also possible to operate the
Unidrive SP from an external Low Voltage DC supply, the supply voltage is dependant
on the drive frame size as detailed in Table 2-1.
Note that this method of drive operation will be referred to as Low Voltage DC (LVDC)
operation through the remainder of this document.
Table 2-1 Low Voltage DC operating range
Drive size
1
2
3
4
5
6
SPMA/D
*Size 4 200V drives have a continuous Low Voltage DC range of 48V to 72V.
The values given in Table 2-1 above are for a typical battery supplied system, this
includes charging of the battery.
If no regen energy is present it is possible to use slightly higher voltage levels.
The AC supply and DC supply must not be connected at the same time, seamless
6
Continuous operating range of a drive
supplied by low voltage DC (Vdc)
48
48-72
48-72
48-96*
48-96
48-96
48-96
Unidrive SP Low Voltage DC Installation Guide
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