1. Overview

AN3550 series speed monitoring receives signals from a magneto-electric tachometric sensor or Proximity sensor; the original signals from the sensor are converted into digital signals by a signal interface unit; the digital signals are transmitted to an embedded microcontroller unit (MCU), and are then identified, judged, processed and compared by software and output by output units, thus implementing online monitoring and protection of device speed.

2. Purposes

Online monitoring and protection of rotary machine speed;

Zero-speed survey control;

Over-speed protection;

Key-phase signal output.

3. Functions

Highlight digital display unit: To display real-time vibration value;

Plate-type touch keyboard: Field programming parameter setting;

Standard signal output: 4-20mA;

On-off output: two-stage alert normally open/closed contact output;

LED indicator: To display various statuses;

Buffer interface: Sensor original signal buffer output.

4. Features

Perfect self-inspection and diagnosis function; when a failure occurs, current output is 0mA, and "Not Ok" LED on the panel is on;

Embedded microcontroller unit (MCU); an E2PROM data storage unit (for important parameters) and a FLASH process program storage unit are integrated in the chip;

Power unit: a DC-DC/AC-DC module power supply realizes ultra-width power input and isolated output;

High/low velocity measuring systems implement precision measurement of zero and low (turning) speed.

5. Application

Application Fields:

Power plants (thermal, hydro, nuclear and wind)

Metallurgy (steel mills and aluminium manufacturers, etc.)

Petrochemical engineering (refining and chemical, coal chemical industry and chemical fertilizers, etc.)



Mine (coal and iron mines)

Hydraulic engineering (reservoirs and pump stations), etc.

Monitored equipment:

Steam turbines;


Water pumps;

Water turbines;

Air blowers;

Coal breakers;


Rotary machines like fans.

6. Technical Specifications


Magneto-electric sensor: 

Passive, outputting pulse signals changing with speed frequency;

Mounting clearance: 1mm±0.2mm.

Magneto-resistive sensor:

Passive, outputting TTL level signals changing with speed frequency;

Mounting clearance: 2.0mm±0.5mm.

Proximity sensor: Φ8 probe

Sensitivity: 7.87mV/μm (200mV/mil)

Output voltage: -2 ~ -18VDC;

GAP voltage: -10VDC.

Note: Mounting clearance is determined based on a 1mm mechanical distance between tooth crest and probe or -10VDC output voltage of preamplifier; mechanical distance is firstly considered so as to prevent the probe from being damaged due to the eccentric shaft.

Measuring range

Over-speed protection/standard speed:

Range: 0-9999rpm

Precision: ±0.5%±1 rpm

Zero speed:

Range: 0-99.99rpm

Precision: ±0.5%±0.01 rpm

Key phase:

Output square (TTL) level signal

Note: Range can be set by field programming.

Power supply:

DC supply: 24VDC (18-36V);

AC supply: 220VAC (185-260V)/47-63Hz;

AC supply: 110VAC/47-63Hz;

Overall power consumption: ≤ 5W.

Standard signal output:

Active 4-20mA (corresponding to upper range)

Drive load: ≤750Ω

Effective transmission distance: ≤ 300m (1,000 feet).

Relay output:

Two-stage threshold (Alert, Danger) programmable setting, normally open/closed dry contact output, configurable whole range, with an error ≤0.1%;

Insulation resistance: ≥1000MΩ;

Contact capacity: 2A/30VDC, double-pole double-throw (DPDT);

Alarm-delay: 0.1-60S, default: 0.5S;

Alert lock: Defaulting to non-locking.

Physical property:

Boundary dimension: 160(W)×80(H)×120(D)mm  6.3(W)×3.15(H)×4.7(D)in

Weight: 1kg.

Way of installation:

Open hole installation:

Hole size: 152 (W) × 76 (H) mm, 6.0(W) ×3.0(H)in

Environmental restrictions:

Operating temperature: -30℃ ~ +65℃ (-22oF ~ +150 oF);

Storage temperature: -40℃ ~ +85℃ (-40oF ~ +180 oF);

Relative humidity: 0 ~ 95% (non-condensing).

Executive standards

The United States Petroleum Association Standard: API 670

Safety certificate: CE;

Protection level: IP56;

Anti-electromagnetic interference: EMC/LVD

Refer to EN55011\ EN 61010\ EN50081\EN50082.

7. Ordering information

AN3551/52/53- speed/zero speed/key phase




Standard Configuration Model:

Revolution speed: AN3551-00-00-00-00-00-02-60 (assorted with AN1920 sensor)

Zero speed: AN3552-01-00-00-00-00-02-60 (assorted with AN1920 sensor)

Key phase: AN3553-02-02-00-00-00-02-01 (assorted with AN1808 Proximity Sensor)

A: Range limit

00--0 ~ 9999rpm (standard)

01--0 ~ 99.99rpm (zero speed)

02--Square wave phase signal output (key phase)

Note: Range can be set by field programming.

B: Sensor type:

00--AN1920 passive magneto-electric sensor

01--AN1910 active magneto-resistive sensor

02--AN1808 Proximity sensor (φ8 probe)


Note: It is recommended that magneto-electric probe be used for over-speed/revolution speed/zero-speed protectors, with speed measurement of multi-tooth fluted disc, and active magneto-resistive or eddy-current probe be used for key-phase protector (φ8 probe).

C: Relay output (DPDT):

00--Double dry contact output (Alert, Danger)

01--Single dry contact output (Alert)

02--No relay output

D: Standard signal output:

00--4 ~ 20mA standard current output

01--1 ~ 5V standard voltage output

02--RS 485 communication interface output

E: Power supply

00--24VDC (18 ~ 36V)



F: Way of installation

00--Guide rail installation DIN35mm

01--Base plate installation

02- Open hole installation

G: Tooth number (key or slot number)



XX--Others (represented by a figure)

Note: Please note if you select other options, If you have any questions, please consult the technical department.


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