Installation manual

44 Magnitude™ Frictionless Centrifugal Chillers – Model WMC IM 1029-2
EMI
Radiated EMI is similar to an unwanted radio broadcast being emitted from the power lines. There are many
pieces of equipment that can generate EMI, variable frequency drives included. In the case of variable frequency
drives, the electrical noise produced is primarily contained in the switching edges of the pulse width modulation
(PWM) controller.
As the technology of drives evolves, switching frequencies increase. These increases also increase the effective
edge frequencies produced, thereby increasing the amount of electrical noise.
The power line noise emissions associated with variable frequency and variable speed drives can cause
disturbances in nearby equipment. Typical disturbances include:
• Dimmer and ballast instability
• Lighting disturbances such as flashing
• Poor radio reception
• Poor television reception
• Instability of control systems
• Flow meter totalizing
• Flow metering fluctuation
• Computer system failures including loss of data
• Thermostat control problems
• Radar disruption
• Sonar disruption
RFI
Three-phase filters are supplied as an option for factory mounting in the compressor power panels. They use a
combination of high frequency inductors and capacitors to reduce noise in the critical 150 kHz to 30 MHz
frequency range. The inductors act as open circuits and the capacitors act as short circuits at high frequencies
while allowing the lower power line frequencies to pass untouched. The filters assist with cost effective
compliance to Electro Magnetic Compatibility (EMC) directives, in a compact, efficient, light-weight design.
The high common mode and differential mode reduction in the critical 150kHz to 30MHz frequencies assures
that potential interference from AC drives is reduced or eliminated.
The filters are current-rated devices. In order to properly size a filter, it is necessary to know the operating
voltage and the input current rating of the drive. No derating or re-rating is necessary when applying the filter at
voltages that are less than or equal to the maximum voltage listed on the filter.
The IEEE 519-1991 Standard
The Institute of Electrical and Electronics Engineers (IEEE) has developed a standard that defines
acceptable limits of system current and voltage distortion. A simple form is available from Daikin that
allows the system designer to determine compliance with IEEE 519-1991.
Line reactors, isolation transformers, or phase-shifting transformers can be required on some installations.
Fuses
All WMC chillers have power fuses upstream of the compressors. Models WMC 145S, 250D and 290D have
the fuses in the power panel. Models WMC 145D and 150D have them in the top of the compressor, accessible
by removing the compressor top cover.
Fuses are: Manufacturer: Littelfuse, Class: T, Amps: JLLS 175, Volts: 600V.
System Pumps
Operation of the chilled water pump can be to 1) cycle the pump with the unit, 2) operate continuously, or 3)
start automatically by a remote source.
The cooling tower pump must cycle with the compressor. The holding coil of the cooling tower pump motor
starter must be rated at 115 volts, 60 Hz, with a maximum volt-amperage rating of 100. A control relay is
required if the voltage-amperage rating is exceeded. See the Field Wiring Diagram on page 41 or in the cover of
control panel for proper connections. All interlock contacts must be rated for no less than 10 inductive amps.
The alarm circuit provided in the control center utilizes 115-volts AC. The alarms must not draw more than 10-
volt amperes.