Marley / MC Fluid Cooler / Specifications: Options
Specifications | Specification Value |
in the off position for safety. The VFD system shall receive a speed reference signal from the Building Management System monitoring the tower fluid tem- perature. As an option to receiving the speed reference signal from a building management system, the drive must have the capability to receive a 4-20 ma temperature signal from an RTD trans- mitter. The VFD shall have an internal PI regulator to modulate fan speed main- taining set point temperature. The drive's panel display shall be able to display the set-point temperature and cold-fluid temperature on two separate lines. The bypass shall include a complete mag- netic 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 con- stant 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 tempera- tures while the VFD is in a by-pass mode. Operator controls shall be mounted on the front of the enclosure and shall con- sist of start and stop control, bypass/VFD selection, Auto/Manual selections, manu- al speed control. To prevent heating prob- lems 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 manufacturer shall supply VFD start-up assistance. Tower vibration testing throughout the speed range is required to identify and lockout any natu- ral frequency vibration levels which may exceed CTI guidelines.
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 IP52 indoor or IP14 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
