Product Overview

The Emerson A6312 monitors critical rotating machinery with high reliability. This dual-channel module belongs to the AMS 6500 protection system. It measures speed, phase, zero speed, and direction of rotation. The A6312 works with steam turbines, gas turbines, compressors, and hydro machinery. You can configure this monitor for redundant tachometer operation. Automatic switchover occurs when primary sensors fail. The module integrates seamlessly with PlantWeb, Ovation, and DeltaV control systems.

Key Features

• API 670 compliant for machinery protection

• Hot swappable module reduces downtime

• Remote selectable limit multiply and trip bypass

• Rear buffered proportional outputs (0/4-20 mA)

• Self-checking facilities monitor hardware, power, temperature, sensors, and cables

• 6TE width for AMS 6000 rack (19")

• 8TE width for AMS 6500 rack (19")

Transducer Inputs

Input Specifications

Compatible Emerson Sensors

• Sensor Part Numbers: 6422, 6423, 6424, 6425

• Compatible Drivers: CON 011/91, 021/91, 041/91

The A6312 requires displacement sensors for both speed and key measurements. Speed measurements use a toothed wheel, keyway, or gear as the target. Key measurements need a once-per-revolution target (not a toothed wheel). This distinction is critical for proper phase measurement.

Measuring Range

• Adjustability: Continuously adjustable with configuration software

• Smallest Range: 2 V

• Largest Range: 0 - 30 V

• Resolution: 1% of full scale value

Sensor Power Supply

• Type: Separate buffered sensor supply

• Isolation: Galvanically separated from all system voltages

• Protection: Open and short circuit proof

• Nominal Voltage: -26.75 VDC

• Available Current (Nominal): 20 mA

• Available Current (Maximum): 35 mA

Measurement Modes

The Emerson A6312 supports hot-configurable measurement modes:

Speed Measurement (Each Channel)

• Forward and reverse rotation detection with trigger wheel

• Trigger marks: 1 to 255

• Maximum frequency: 20 kHz

• Pulse width time window: 5 - 10 msec

Key Pulse Detection (Each Channel)

• Standard configuration: 1 key mark on the shaft

• Multiple key marks possible: Phase changes with each start-up

Zero Speed Monitor (Each Channel)

• Detection method: Measures time between two pulses

• Configurable range: 1 - 1700 seconds

• Direction: Forward or reverse

Combined Channel Functions

• Direction of rotation detection: Uses two trigger marks (one phase shifted)

• Speed difference detection: Between two trigger wheels (adjustable in RPM)

Front Panel Indicators and Outputs

LED Indicators

Front Panel Buffered Outputs

• Number of outputs: 2

• Signal range: ±10 V (input signal reduced by factor 0.15)

• Load impedance: >100 kΩ

• Frequency range: 0 Hz - 16 kHz (-3 dB)

Mini DIN Configuration Socket

• Function: Module interface for configuration, parameter setting, and status monitoring

• Protocol: RS-232

Handle

• Purpose: Easily remove card from rack

• Identification plate: For module and sensor labeling

Rear Outputs

Current Mode Outputs

• Signal: 0/4-20 mA for each channel (proportional to main value)

• Protection: Open and short circuit proof

• Permissible Load: <500 Ω

• Accuracy: ±1% of full scale

• Settling Time: Configurable from 0 to 10 seconds

Pulse Outputs

• Frequency range: 0 Hz - 20 kHz for each channel

• Protection: Open and short circuit proof

• Permissible Load: >10 kΩ

TTL Pulse Output

• Signal: 0 Hz - 20 kHz for each channel (0 - 20 kHz)

• Protection: Open and short circuit proof

• Permissible Load: >10 kΩ

Alarm Setpoints

Alert Configuration

Danger Configuration

Self-Checking and OK Monitoring

The Emerson A6312 continuously monitors these conditions:

• Power supply status

• Sensor and cable integrity

• Module hardware health

• Overload conditions

• Internal temperature

• System watchdog

OK Indication (Normally Closed)

• Green LED off: Channel not OK condition

• Flashing green LED: During delay time

• Failure reason: Readable from communication bus

Redundant Mode Operation

The A6312 supports redundant tachometer configuration:

• Automatic switchover from primary to backup tachometer

• Switchover triggers: Sensor gap voltage monitoring and pulse counting/comparison

• Installation requirement: Main and failover sensors must be in the same axial plane

• Phase continuity: Ensured upon failover when sensors share the same axial plane

Limit Multiply and Trip Bypass

• Limit Multiply Factor: Remote relay input, 1.00 - 4.99

• Trip Bypass: Remote relay input

Environmental Specifications

General

Temperature and Humidity

Vibration (IEC 68-2, part 6)

• 0.15 mm displacement: 10 - 55 Hz

• 19.6 mm/s² acceleration: 55 - 150 Hz

Shock (IEC 68-2, part 29)

• Peak acceleration: 98 m/s²

• Duration: 16 ms

EMC Resistance

• Standards: EN50081-1 / EN50082-2

Power Specifications

• Maximum power consumption: 6 W

• Current draw: 250 mA at 24 VDC

• Configuration protection: Password enabled

Physical Dimensions

Module (PCB/EURO card format per DIN 41494)

Width Variations

Rack Compatibility

• Height: 128.4 mm (5.055") (3 HE)

• Space requirement: 1 slot

• Modules per 19" rack: 14 modules

The A6312 fits into both IMR 6000/10 and IMR 6000/30 racks. Its 3U size reduces cabinet space by half compared to traditional 6U cards.

Weight and Packaging

• Net weight: approximately 320 g (0.705 lbs)

• Gross weight: approximately 450 g (0.992 lbs) including standard packing

• Packing volume: approximately 2.5 dm³ (0.08 ft³)

Ordering Information

Installation Guidelines

Follow these steps to install the Emerson A6312 module:

1. Turn off power to the AMS 6500 rack completely.

2. Identify an empty slot in the 19" rack chassis.

3. Slide the A6312 into the chosen slot along the guide rails.

4. Push firmly until the rear connectors seat properly.

5. Tighten the front panel screws to secure the module.

6. Connect displacement sensors to the front panel inputs.

7. Wire rear outputs to your control system as needed.

8. Apply power to the rack and observe LED status.

9. Configure the A6312 using AMS 6500 configuration software.

10. Perform a function test before placing the machine into service.

Do not remove the Emerson A6312 while power is applied without bypassing trip outputs. Use shielded twisted pair cables for all sensor connections. Maintain proper sensor gap voltage according to the displacement sensor specifications.

Packaging List

• 1 x Emerson A6312 Speed and Key Monitor module

• 1 x front panel identification plate

• 1 x quick start configuration guide

Common FAQs

Q1: Can the A6312 measure speed from a magnetic pickup sensor?
A1: No, the A6312 requires eddy current displacement sensors. Use the A6313 module for magnetic pickup inputs instead.

Q2: What is the maximum RPM the A6312 can measure?
A2: The Emerson A6312 measures up to 65,535 RPM. The input frequency range is 0 to 20,000 Hz with a 1 to 255 trigger wheel.

Q3: Does the A6312 support reverse rotation detection on both channels?
A3: Yes, each channel on the A6312 independently detects forward and reverse rotation. You need a phase-shifted second trigger mark for direction detection.

Q4: How do I configure the A6312 alarm setpoints?
A4: Use the AMS 6500 configuration software connected via the Mini DIN socket on the A6312 front panel. The module supports password protection for configuration changes.

Q5: Is the A6312 compatible with existing Bently Nevada monitors?
A5: The Emerson A6312 is designed for AMS 6500 racks only. Physical adapters are not available for Bently Nevada 3500 racks.