Marley IMI 686B - User Manual

IMI 686B vibration switch
INSTALLATION - OPERATION - MAINTENANCE
Z1070990_B ISSUED 1/2020 READ AND UNDERSTAND THIS MANUAL PRIOR TO OPERATING OR SERVICING THIS PRODUCT.
user manual

Summary

Product Overview

General Features

Key capabilities including testing, factory programming, remote reset, trip-point repeatability, and environmental resistance.

Installation and Operation

Sequence of Operation and Reset

Details normal operation, trip conditions, latching, and the procedure for resetting the vibration switch.

Wiring

Two-Wire Control Circuit with SPST Switch

Explains the typical two-wire control circuit connection for the IMI 686B vibration switch with an ABB VFD.

Wiring Diagrams

IB1 Interface Box Wiring Diagram

Illustrates wiring for the Marley IB1 interface box for alarm and control with the vibration switch.

Frequently Asked Questions

Voltage Ratings

Specifies the available voltage ratings for the vibration switch.

Sensor Technology and Operation

Explains sensor type, factory programming, contact config, and reset method for the vibration switch.

Switch Mounting and Design

Covers mounting stud, typical locations, and explosion-proof design availability.

Cable and Wiring Extensions

Addresses cable length, lead extension, and conduit requirements for the vibration switch.

System Integration

Details interfacing the switch with Marley AIO panels and electromechanical motor starters.

Product Specifications

Overview

1. Function Description
2. Important Technical Specifications
3. Usage Features
4. Maintenance Features

The IMI 686B vibration switch is a specialized device designed for cooling tower applications, offering robust vibration protection for mechanical equipment. Its primary function is to monitor vibration levels and trigger a shutdown if continuous high vibration is detected, preventing potential damage to the cooling tower's components.

Function Description:

The IMI 686B operates as a normally closed (N.C.) switch. In its normal state, with or without power, the switch is closed, allowing mechanical equipment to operate. Once powered, it remains closed. If the switch detects a continuous high vibration level for 3 seconds or more, it will open and latch in an open state. This 3-second delay is crucial for preventing nuisance tripping during startup or momentary vibration spikes, allowing the fan to accelerate through critical frequencies. When tripped, the cooling tower has experienced abnormal vibration and requires inspection before being returned to service. To reset the switch after a vibration event, power must be discharged and then reapplied. This can typically be achieved by cycling power at the VFD (Variable Frequency Drive) or motor starter line side disconnect. For VFDs, it's essential to keep power off for 30 seconds to allow capacitors to fully discharge. The switch is factory-programmed by SPX specifically for cooling tower vibration protection, and reprogramming is generally not recommended unless directed by SPX.

Important Technical Specifications:

• Sensor Type: Piezoelectric accelerometer, sensing vibration velocity for consistent results. This solid-state design means there are no mechanically moving parts.
• Switch Contact: Single, normally closed (N.C.) contact, factory-programmed to latch open upon a trip.
• Contact Rating: Rated at 20mA. It's crucial not to exceed this value. Most VFDs utilize a 24 VDC low current safety circuit, which is well within this limit.
• Trip Point: 0.7 ips peak with a 3-second delay.
• Voltage Ratings: 24 to 240 VDC/AC - 50/60Hz.
• Enclosure: NEMA4X/IP68 hermetically-sealed stainless steel enclosure, designed to withstand harsh internal cooling tower environments. An explosion-proof model (Part Number 2695604) is also available, meeting CSA Class 1, Div 2, Groups A, B, C, and D.
• Cable: Integral 30' (9m) cable with a molded connection at the switch and flying ends at the opposite end (for Part Number 2598732). The molded connection prevents water vapor and contaminants from entering the switch or its connection points. The cable is rated for outdoor use, and local codes should be consulted for conduit requirements. The cable is permanently attached and cannot be replaced independently of the switch.
• Mounting: Standard 1/4-28 UNF threads, typically mounted on a gearbox. Torque the switch to 2-5 ft·lbf (3-7 N·m) during installation.
• Operating Temperature Range: -40 to 185°F (-40 to 85°C).
• Standards: CE (for Standard Vibration Switch), CSA and UL (for IB1 Interface Box), CSA (for Explosion-Proof Vibration Switch).

Usage Features:

• Remote Reset Capability: The switch can be reset remotely by cycling power, eliminating the need to physically enter the cooling tower.
• Built-in Delay: The 3-second delay prevents nuisance tripping during fan startup or from momentary vibration spikes.
• Vibration Velocity Monitoring: Monitors vibration velocity, providing consistent and reliable results.
• Low-Frequency Vibration Sensing: Capable of sensing low-frequency vibrations more effectively than traditional mechanical switches.
• Two-Wire Circuit: Designed as a 2-wire combination power and control circuit, adaptable to most VFD circuits.
• Interface Box (Marley IB1): An optional Marley IB1 interface box (Part Number 2600177) is available for applications requiring two contacts (e.g., for an alarm circuit at the BMS) or for interfacing with motor starters. The IB1 box provides a reset push button and a tripped indicating light. It is recommended when wiring the vibration switch to a motor starter operating coil to avoid damage from high inrush current.

Maintenance Features:

• Maintenance-Free Design: The IMI 686B vibration switch is designed to be maintenance-free.
• Hermetically Sealed: The hermetically-sealed stainless steel enclosure protects internal components from humidity and chemical exposure, contributing to its longevity and reliability in harsh environments.
• Factory Programmed: Being factory-programmed for cooling tower applications, it requires no field adjustments for its primary function.

In summary, the IMI 686B vibration switch is a robust, reliable, and specialized solution for protecting cooling tower mechanical equipment from excessive vibration, offering advanced features like remote reset, intelligent tripping delays, and a durable, maintenance-free design.

Marley IMI 686B Specifications

General

Brand	Marley
Model	IMI 686B
Category	Switch
Language	English