SPX Cooling Technologies 1200 Specifications, Specification Value, Marley Premium VFD System

Marley / Sigma 1000/1200 CoolingTower / Specifications: Options

Specifications Specification Value

to modulate fan speed maintaining set point temperature. The drive's panel dis- play shall be able to display the set-point temperature and cold-fluid temperature on two separate lines. The bypass shall include a complete magnetic bypass circuit and with capability to isolate the VFD when in the bypass mode. Transfer to the bypass mode shall be manual in the event of VFD failure. Once the motor is transferred to the by-pass circuit the fan motor will run at constant full speed. The bypass circuit will not modulate ON and OFF based on fluid temperature. The application must be able to handle very cold fluid temperatures while the VFD is in a by-pass mode. Operator controls shall be mounted on the front of the enclosure and shall consist of start and stop control, bypass/VFD selection, Auto/ Manual selections, manual speed control. To prevent heating problems in the fluid cooloer fan motor and to assure proper gear reducer lubrication the VFD system shall de energize the motor once 25% motor speed is reached and cooling is no longer required. The fluid cooler manu- facturer shall supply VFD start-up assis- tance. Tower vibration testing throughout the speed range is required to identify and lockout any natural frequency vibra- tion levels which may exceed CTI guide- lines.

Marley Premium VFD System

6.4Add the following paragraph in the Mechanical Equipment section when VFD is used as a stand alone system: A complete UL listed Variable Speed Drive system in a NEMA 12 indoor

or NEMA 3R outdoor enclosure shall be provided. The VFD shall use PWM technology with IGBT switching and integrated bypass design. VFD output switching shall not cause mechanical issues with gearbox teeth or drive shafts. The VFD shall catch a fan spinning in the reverse direction without tripping. The panel shall include a main disconnect with short circuit protection and external operating handle, lockable in the off posi- tion for safety. The system shall include a solid state, PI temperature controller to adjust frequency output of the drive in response to the tower fluid tempera- ture. The temperature of the fluid and

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