Frequently Asked Questions

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

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.

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

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.

*Present in bi-directional versions only

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.

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:

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.

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.

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.

• 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.

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.

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.

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.

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.

907 Alignment Resources

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

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. 

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.

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

PVC, Aluminum, and Stainless Steel.

• Exact shaft diameter
• Maximum RPM of the shaft
• Maximum temperature the wrap will encounter
• Any corrosive chemicals or solvents present
• Any space restrictions.

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

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.

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.

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.

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

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.

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

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#).

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.