Zero Speed Switch Model ZS12

ZS12 Zero Speed Switch with Replaceable Sensor

Looking for ways to prevent equipment failures and save money? The Phares Model ZS12 Zero Speed Switch ensures precision and productivity in your operations. This rugged all-in-one shaft speed monitoring device is designed for outdoor use. It combines both sensor and relay, no separate control box required. Capable of switching up to 5 amps. Equip your system with the ZS12 Zero Speed for reliability and peace of mind.

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Part Numbers

Part Number	Input Voltage	Contacts (5 Amp)	Target
ZS12-AF	100-240 VAC	N.O./N.C.	Ferrous
ZS12-AM	100-240 VAC	N.O./N.C.	Magnetic
ZS12-DF	9-36 VDC	N.O./N.C.	Ferrous
ZS12-DM	9-36 VDC	N.O./N.C.	Magnetic

Product Overview

The Phares Model ZS12 Zero Speed Switch is a robust, all-in-one device designed to safeguard your industrial machinery. It features both relay and replaceable sensor, making it ideal for over-speed, under-speed, or zero-speed monitoring. This device protects your conveyors and other equipment from unexpected slowdowns or stops.

The ZS12 Zero Speed Switch offers precise and accurate speed measurement with its adjustable setpoint, controlled by a multi-turn trim pot. It can react in a fraction of a second if your conveyor or machine suddenly stops.

When your machine’s shaft speed hits the setpoint, the ZS12 Zero Speed Switch’s relay output changes its state. It remains in this state until the machine slows down too much or stops completely.

The Phares ZS12 Zero Speed Switch also comes with three diagnostic LEDs:

Power: Indicates the unit is receiving power.
Pulse: Shows if there are pulses coming from the sensor input signal.
Relay: Displays the current status of the relay.

You can easily adjust the setpoint using the multi-turn trim pot for precise control.

The ZS12 Zero Speed Switch features isolated relay contacts, which makes it incredibly simple to integrate into both new and existing systems. It’s also an excellent choice for replacing older, obsolete zero-speed switches.

Applications

The ZS12 Zero Speed Switch is highly versatile and can be installed on a wide range of industrial equipment where shaft speed monitoring is crucial. This includes, but isn’t limited to:

Augers
Bucket elevators
Conveyors
Exhaust fans
Grinders
Turbines

It’s suitable for virtually any application requiring reliable shaft speed oversight.

Features

Self-contained zero speed switch with relay and low profile, replaceable sensor
Isolated relay contacts switch up to 5 amps
Senses magnetic and high iron content targets (gear tooth, key stock, bolt head, etc.)
Available for 100–240 VAC or 9–36 VDC power. Select the appropriate ZS12 part number for the required supply voltage.
LED indicators for instant visual confirmation
Precision trim pot for accurate relay setpoint adjustment

Benefits

Faster than pushing ‘Emergency Stop’
No additional control box needed
Suitable for outdoor use and in wash down areas
Over speed, under speed, or zero speed detection
Extend the lifespan of your equipment
Stop conveyor “domino” effect
Detect unexpected load increase
Reduce belt breaks

Specifications

Operating Voltages	100-240 VAC (for Model No. ZS12-A) 9-36 VDC (for Model No. ZS12-D)
Current Draw	116 mA
Circuit Protection	Internal ½ amp fuse, non-replaceable
Operating Temperature	-40°F to 140°F
Speed Detection Range	0.03 to 25,000 RPM
Threads	1/2-inch NPT
Relay	Output: SPDT Form ‘C’ dry relay contact (N.O/N.C.) Contact Rating: 5 A at 120 VAC; 5 A at 30 VDC Maximum switching frequency: 1,800 operations/hr (under rated load) Life expectancy: Mechanical 10,000,000 operations min. (at 1,800 operations/hr) Electrical 100,000 operations min. (at 1,800 operations/hr)
Relay Setpoint Adjustment Range	Standard: 1-100 RPM, 1 Pulse Per Revolution Custom parameters are available.
Extend the Sensor	The Sensor may be extended from the enclosure with 1/2-inch conduit.
Housing Material	Cast Aluminum
Sensing Distance to Target (Gap)	1/16″ to 5/16″ using Ferrous Target (Gear Tooth Wheel, Bolt Head, Key Stock, etc.) Sold separately: 1/16″ to 3/8″ using Phares High Density Magnetic Disk 1″ maximum using Phares Standard Magnetic Disk 1″ maximum using Phares Magnet, Part No. SM-100 2″ maximum using Phares Magnet, Part No. RM-100
Minimum Gear Tooth Target Sizes	1/8″ gear tooth length, width, depth and gap.
Gear Tooth Target Material	Low carbon steel (high iron content)

Options

Custom Sensor Length
Custom Relay Set-Point Adjustment Range
Fixed Set-Point
Relay Latch

Wiring & Installation

Installation is simple:

Mount the ZS12 aiming the sensor at a rotating target such as a bolt head, key stock, flat washer, or magnet. Ferrous targets must have high iron content. Stainless steel and other low-ferrous materials may not be detected reliably.
Properly Ground the aluminum enclosure.
Connect relay contacts (N.O. or N.C.) to your control circuit.
Adjust the relay setpoint to match your application requirements using the trim pot inside the ZS12 enclosure.
A 5 amp external fuse is recommended to help protect the ZS12 relay contacts from possible overload. Wire the fuse in-line to the Relay “COM” terminal.

LED indicators show power, sensor, and relay status at a glance.

Frequently Asked Questions

Do I need a separate controller?: No. The ZS12 includes both sensor and relay output.

What happens if the shaft stops?: When a stop or under speed condition is detected, the relay LED turns off and the relay disengages, returning to its default (normal) state.

How close should the sensor be to the target?

For ferrous targets, a minimum of 1/16″ to 5/16″ (1.6 to 7.9 mm).

Magnetic Targets sold separately:
1/2″ to 3/8″ using Phares Magnetic Disk
1″ maximum using Phares Magnet, Part No. SM-100
2″ maximum using Phares Magnet, Part No. RM-100