Marley / Sigma F Series CoolingTower / Specifications: Options | 25 |
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| Specifications |
| Specification Value |
| Fan Motor Variable Speed Drive: |
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| Marley All Weather ACH550 System |
| ■ Marley VFD drive systems are designed to combine absolute |
6.4 | Add the following paragraph in the |
| temperature control with ideal energy management. The cool- |
| ing tower user selects a cold water temperature and the drive | ||
| Mechanical Equipment section when |
| system will vary the fan speed to maintain that temperature. |
| VFD is used with customers Building |
| Precise temperature control is accomplished with far less stress |
| Management System: A complete UL |
| to the mechanical equipment components. The improved energy |
| listed Variable Speed Drive system in |
| management provides fast payback. Indeed, many utilities offer |
| a NEMA 1 indoor, NEMA 12 indoor or |
| generous rebates for users having installed VFD drives. |
| NEMA 3R outdoor enclosure shall be pro- |
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| vided. The VFD shall use PWM technol- |
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| ogy with IGBT switching and integrated |
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| bypass design. VFD out put switching |
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| shall not cause mechanical issues with |
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| gearbox teeth or drive shafts. The VFD |
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| shall catch a fan spinning in the reverse |
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| direction without tripping. The panel shall |
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| include a main disconnect with short |
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| circuit protection and external operating |
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| handle, lockable in the off position for |
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| safety. The VFD system shall receive a |
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| speed reference signal from the Building |
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| Management System monitoring the |
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| tower fluid temperature. As an option |
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| to receiving the speed reference signal |
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| from a building management system, the |
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| drive must have the capability to receive |
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| a |
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| RTD transmitter. The VFD shall have an |
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| internal PI regulator to modulate fan |
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| speed maintaining set point temperature. |
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| The drive's panel display shall be able |
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| to display the |
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| lines. The bypass shall include a complete |
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| magnetic bypass circuit and with capabil- |
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| ity to isolate the VFD when in the bypass |
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| mode. Transfer to the bypass mode shall |
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| be manual in the event of VFD failure. |
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| Once the motor is transferred to the |
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| constant full speed. The bypass circuit |
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| will not modulate ON and OFF based on |
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| fluid temperature. The application must |
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| be able to handle very cold fluid tempera- |
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| tures while the VFD is in a |
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| Operator controls shall be mounted on |
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| the front of the enclosure and shall con- |
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| sist of start and stop control, bypass/ |
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| VFD selection, Auto/Manual selections, |
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| manual speed control. To prevent heating |
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| problems in the fluid cooloer fan motor |
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| and to assure proper gear reducer lubrica- |
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| tion the VFD system shall de energize the |
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| motor once 25% motor speed is reached |
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