Phares Zero Speed Switch Sensor Models ZS09P and ZS09R look almost identical. They are enclosed inside threaded sensor housings which appear very similar. Both contain relay, sensor, and control circuitry. Relay contacts are Form ‘C’ and are isolated from internal circuitry.
The main difference between the Phares ZS09P and ZS09R Zero Speed Switches is the amperage rating of the relay contacts. The “P” in the part number stands for Power Relay and can switch up to 5 Amps. It is designed for use in a control circuit.
The “R” in the part number stands for Reed Relay and can switch 1/4 Amp, pilot duty. It is designed for switching logic inputs, such as with a PLC, or an ‘ice cube’ relay.
Another difference it the ZS09R Zero Speed Switch is smaller in diameter than the ZS09P.
Below is a table summarizing the key differences between the two switches.
| FEATURE | ZS09P | ZS09R |
| DIFFERENCES | ||
| Type of Relay | Power Relay | Reed Relay |
| Relay Contact Load (Max.) | 5 Amps | 1/4 Amp |
| Dimensions | 1-1/16″ Diameter x 4″ Long | 7/8″ Diameter x 4″ Long |
| Thread | 17/16-14 2.0″ Inches | 7/8-14 2.0″ Inches |
| Weight | 6 oz. | 4 oz. |
| SIMILARITIES | ||
| Set Point Adjustment | Precision Trim Pot | Precision Trim Pot |
| LED Indicators | Yes | Yes |
| Isolated Relay Contacts | Yes | Yes |
Application Description A power plant has a coal conveyor located in a high temperature environment.…