Skip to main content

Frequently Asked Questions

What is the standard cable used on my Hall Effect sensor?

-conductor, Shielded, PVC jacketed, 22-gauge wire.

What type of cable should I use?

Electro-Sensors uses and recommends a high-quality 22 AWG audio/instrument signal cable.

  • For 2 conductor cable use a Belden 8761, or equivalent, shielded cable.
  • For 3 conductor cable use a Belden 8771, or equivalent, shielded cable.
  • For 4 conductor cable use a Belden 8723, or equivalent, shielded cable.
  • For 6 conductor cable use a Belden 9260, or equivalent, shielded cable.
What are the standard cable lengths available from the factory?

Sensors are available with 10', 50', 100', and multiples of 100' of cable.

How far can I run my sensor cable wire?

The standard cable length on most Electro-Sensors' sensors is 10 feet, however, our standard Hall-Effect Sensors can be mounted up to 1500 feet away from one of our meters or modules when using a quality cable.

What is each of the wires on my sensor for?

ESI 906/907

ESI Prox

ESI Other









Signal A




Signal B*




*Present in bi-directional versions only

What type of Output does my sensor give?

Electro-Sensors standard Hall-Effect Sensors give a NPN Open Collector, current sinking output. The output is a digital square wave alternating from zero to supply voltage. We also have optional PNP Open Collector, current sourcing sensors.

What value pull-up resistor should I use with an Electro-Sensors sensor?

All Electro-Sensors' products have an internal pull-up resistor. However, if you are sending the pulses to a device without one, you will need to supply one. A suitable pull-up resistor can be anywhere from a 1 K-ohm - 3.3 K-ohms, however, be sure not to exceed 25mA on the sensor. Additionally, ensure the resistor is rated for 200% of the expected maximum wattage it will dissipate at 25°C. If using ¼ watt resistors good values are:

DC Supply Resistor in Ohms  Current Watts Dissipated
5-10 volts 1K  5-10 mA .100  (100 mill watt)
12-15 volts 2.2-3.3K 6.8 – 5.45 mA .082   (82 mill watt)
24 volts 4.7K 5 mA .123   (123 mill watt)
What is the maximum working voltage and current my sensor can handle?

Electro-Sensors' Hall Effect sensors can work up to 24 Vdc at 25 mA maximum. However, we strongly recommend an operating current of less than 20 mA.

Do I need a separate DC power supply to power the Hall Effect Sensor?

When using the sensor with an Electro-Sensors product (Speed Switch, Tachometer, etc.) no separate power supply is needed. Those products have a built in supply to power the sensor. If not using with an Electro-Sensors product, check the specifications of that product.

Can my sensor be used with an Intrinsically Safe Barrier?

Yes, Electro-Sensors' Hall Effect, Magnetoresistive, and Digital Ring Kit Sensors meet the requirements of intrinsically safe apparatus and associated apparatus for use in Class I, II, and III; Division I hazardous (classified) locations. ANSI/UL 913-1988 - Category 16.

How do I test my sensor to make sure it is working properly?
  • Electro-Sensors' analog sensors (Models 916, 917) can be tested by disconnecting the sensor from the electronics, and connecting an ohmmeter to the black and clear wires. A properly working sensor would have an ohm reading of approximately 10,000 ohms. Otherwise, contact the factory for details.
  • Electro-Sensors' standard Hall Effect Sensors (Models 906, 907, 931, 932, 933, 1101, 1102, 1201, and 1202) require an electrical test. Please contact the factory for details.
Do I need a two or three piece shaft monitoring system?

Many applications are more suited to having the switch electronics and sensor right at the monitoring point (a two piece system) that way everything is calibrated right there. Other applications require the switch to be remotely mounted from the sensor and disc (a three piece system). Space limitations, environmental considerations, and personal preference all play a part in determining the speed switch system required figure out what you need before installation begins it will save you time and money in the long term.

What type of sensor do I need for my application?

Electro-Sensors offers several different types of sensor housings to meet even the most demanding and diverse of application needs. Our standard aluminum body sensors will work in most applications, but we also have explosion proof sensors and the choice of either stainless steel or PVC sensors for corrosive environments. Our explosion proof sensors are also a great choice for harsh environments such as rock quarries or mining applications where a rugged housing is required to protect the sensing head. All of our sensors can be supplied with high-temp Teflon cable if required for higher temperature applications.

What are my pulse generating options?

Electro-Sensors offers a wide range of shaft end mount pulser discs and over shaft mount pulser wraps. If the end of the shaft to be monitored is readily available, then in many cases, it makes sense to choose a pulser disc to generate pulses. If the shaft end is not available, then you can use a pulser wrap this is a custom made pulse generator that is a split collar that clamps around the shaft and installs in seconds. Over the years we have manufactured thousands of custom pulser discs and wraps, and either way we've got you covered.

What is the difference between RPM range and relay set point range?

Most of Electro-Sensors speed switches can be used to monitor shafts that operate at speeds of up to 10,000 RPM. The relay set point range, however, varies from switch to switch; this range is where the relay will trip when a fault condition occurs. The M100T switch for example has an operating RPM range up to 10,000 RPM, but a set point range of between 5 and 100 RPM. When calibrated the relay will trip somewhere between these 5 and 100 RPM. Knowing the difference between operating RPM range and relay set point range will assist you and save time when specifying a switch for any speed.

How do i properly orient a 907 Sensor with a disc?

FAQs: Discs and Wraps

What tools will I need when installing an end-of-shaft mounted pulser disc?

A No. 21 drill bit, drilled to a depth of .5", and a tap for a 10/32 UNF screw. 

Can I get more Pulse PER REV on the narrow wrap with ΒΌ inch magnets?

A No due to spacing limitations from the mounting bolts, it is the same quantify (number) of magnets for both the ½ inch and ¼ inch. 

Can I bore out my magnet disc? How much?

When needed, our standard discs can be bored out to meet your requirements. The limits for how large you can bore out the discs are listed below. For other pulser discs, please contact the factory.

Disc Maximum bore 
255 Nylon .515"
255 Aluminum, PVC, or Stainless Steel 1"
256 All materials .515"
232 All materials 1"
257 All materials 4"
258 PVC 1"
PD225 PVC .515"
PD455 PVC 1"
PD725 4"
PDE450 2.25"
The end of the shaft I want to monitor is not available to get at. What other options do I have for mounting a magnetic target?

A custom manufactured Pulser wrap that clamps around the shaft that you want to monitor.

What materials can I have my pulser wrap manufactured out of?

PVC, Aluminum, and Stainless Steel.

What information do I need to specify a pulser wrap?
  • Exact shaft diameter
  • Maximum RPM of the shaft
  • Maximum temperature the wrap will encounter
  • Any corrosive chemicals or solvents present
  • Any space restrictions.
What is the maximum number of magnets I can fit on a pulser wrap?

The standard number of magnets on all Electro-Sensors' pulser wraps is 16. However, depending on the outside diameter of a pulser wrap, more magnets may be able to be added. See the following equations or consult the factory for more details.

  • For 1/2" magnets: Max # of magnets = (Wrap OD - .5)*3.14/.65
  • For 1/4" magnets: Max # of magnets = (Wrap OD - .5)*3.14/.35
  • Where OD = Outside Diameter
  • Please Note: an even # of magnets is always needed
How many pulses per revolution does my sensor/disc give?

With a standard Electro-Sensors Hall Effect Sensor, you will get 1 pulse for every 2 magnets (made with magnets alternating in polarity). With an Electro-Sensors Magnetoresistive Sensor, you will get 1 pulse for every 1 magnet. Our standard 255 pulser disc has 16 magnets alternating in polarity.

What type of EZ100 should I be using for a high speed shaft moving in a counter clockwise direction?

The aluminum 255-EZ disc (part#: 700-001502) is the best option for this situation. With the aluminum option, as opposed to the nylon, you can tighten the disc up to 50 pounds or more with a lock washer and Loc-Tite. This will greatly help to secure the disc to the shaft.

FAQs: Other

What types of sensor outputs can be interfaced with my Electro-Sensors equipment?

The standard output being used with Electro-Sensors equipment is NPN Open Collector type. However, much of our equipment can be interfaced with other sensors that are not manufactured by Electro-Sensors. Consult Factory on specific equipment and sensor details, or refer to product data sheets on this web-site.

How do I calculate frequency or Hertz (Hz)?

Frequency is measured in Hertz. Hertz is the measure of pulses per second. Hertz is calculated using the following equation:

  • Hertz = (PPR)(RPM)/60
  • Where PPR = Pulses Per Revolution
  • RPM = Revolutions Per Minute
What is the maximum operating temperature for Electro-Sensors products?

When specified, our sensors, discs, and wraps can be used in areas up to a maximum of 302° F. Our Electronics are rated to 122° F. Consult Factory with exact application concerns.

Is my 4-20 mA or 0-10V output isolated?

Most of our current products have an isolated output. Isolator cards (CVI-50 for example) may be purchased for other equipment.

What if I need to return my product for credit/repair?

Contact Electro-Sensors, Inc. for details and Return Policy at 1-800-328-6170. All products being returned must have a Return Authorization Number (RA#).

What is meant by a Normally Closed or Normally Open contact?

The way to think of a “Normally” closed or open condition is:  The state of the contacts when the relay is sitting on the shelf in the warehouse.   That is their “normal” condition.  When the system is operating correctly they “switch” and are kept that way by an electrical force, current moving through a coil.