Installation manual

IM 1029-2 Magnitude™ Frictionless Centrifugal Chillers – Model WMC 23
Electrical Information
Wiring, fuse and wire size must be in accordance with the National Electric Code (NEC).
Important: The voltage to these units must be within ±10% of nameplate voltage, and the voltage unbalance
between phases must not exceed 2%. Since a 2% voltage unbalance will cause a current unbalance of 6 to 10
times the voltage unbalance per NEMA MG-1, 1998 Standard, it is most important that the unbalance between
phases be kept at a minimum.
Power Wiring
The standard power wiring connection to Magnitude chillers is single point to a common disconnect switch
which is then factory-wired to individual disconnect switches for each circuit.
Proper phase sequence to the unit is not required as far as the unit operation is concerned. Correct motor
rotation is established by the chiller control system regardless of the connected phase sequence.
!
DANGER
Qualified and licensed electricians must perform wiring. An electrical shock hazard exists that
can cause severe injury or death.
The field power wiring required varies depending on unit model, and if optional EMI filters and/or harmonic
filters (including tuning reactors and referred to in this manual as combo harmonic filters) have been ordered.
Factory-mounted and wired line reactors are standard, but discarded when the optional combo harmonic filters
are included. Table 6 gives the various wiring cases as a function of unit model and filters used.
Power Factor Correction Capacitors
Do not use power factor correction capacitors with WMC chillers. Doing so can cause harmful electrical
resonance in the system. Correction capacitors are not necessary since VFDs inherently maintain high power
factors
NOTE: Harmonic filter dimensions, weights, connection size and location are in the Dimension Section
beginning on page 17.
Table 6, Field Wiring Cases
WMC Model
Standard With
Standard Line Reactors
With Optional
EMI Filters
With Optional Combo
Harmonic Filters
With Optional Combo
Harmonic Filters and EMI
WMC 145S
Case 1 Case 7 Case 8 Case 9
WMC 145D, 150D
Case 1 Case 2 Case 5 Case 6
WMC 250D, 290D, 400D
Case 1 Case 2 Case 3 Case 4
Case 1, Field Power Wiring
Case 1 applies to standard units that also include standard line reactors. The standard connection is to two
disconnect switches on multi-point connection or to a single disconnect switch (or optional power block) on
optional single-point connection.
Figure 18, Case 1 Wiring
Multi-Point Single-Point
Disconnect
Switch, Circuit #1
Disconnect
Switch, Circuit #2
Disconnect Switch or
Optional Power Block