User manual

Electrical Connections
81 Liebert
®
DS
™
8.4 Variable Speed Drive
An optional Variable Speed Drive (VSD) is available on some Liebert DS models. The VSD reduces
power consumption by reducing the blower speed to match the unit’s load.
This packaged unit is factory-set and should not require field-adjustment.
NOTICE
Risk of improper program adjustment. Can cause equipment damage and loss of warranty.
The VSD is factory-programmed for proper operation. Altering the VSD program without
authorization from the factory may void the warranty.
8.4.1 VSD Power Supply—Field-Adjustment May Be Required
The installer/startup technician must determine the type of three-phase supply power
(Wye-connected or Delta-connected) being used at the building power distribution panel for the
VSD-controlled unit.
NOTICE
Risk of mismatched input power supply and VSD requirements. May cause equipment
damage and failure.
The EMC filter must be removed from the VSD if the power supply is Delta-connected.
8.4.2 Wye-Connected Power Supply
No control changes are required if the Liebert VSD Control unit will be operated with Wye-connected
power.
Figure 63 Wye-connected power diagram
!
WARNING
Risk of electric shock from leakage current. Can cause injury or death.
Reconnect earth ground if servicing or replacing the variable speed drive (VSD).
!
WARNING
Risk of contact with nearby high speed moving parts. Can cause injury or death.
Do not attempt to adjust or view variable frequency drive settings at the display on the face of
the VSD. Instead, use a remote display (Liebert service item part number 196632P1) and
connect to the VSD remote cable in the extra low voltage electric panel.
NOTE
Emerson requires the Liebert DS to have a grounded supply. The VSD may be damaged if it is
operated on an ungrounded supply.
Phase A
Winding C
Winding A
Winding B
Neutral
Phase B
DPN001944
Rev. 0
Phase C