Bulletin No. PRS1-H Drawing No. LP0026 Released 8/05 Tel +1 (717) 767-6511 Fax +1 (717) 764-0839 www.redlion.net MODEL PRS1 - PLUG-IN SPEED SWITCH z 5 RANGES, FROM 0.1 Hz to 10 KHz z OVER-SPEED, UNDER-SPEED, OR ZERO-SPEED DETECTION z 4 OPERATING MODES z REPEATABILITY TO 1/2% OF MAX. RANGE z LED RELAY ON INDICATOR z PROGRAMMABLE INPUT CIRCUIT ACCEPTS OUTPUTS FROM A VARIETY OF SENSORS DESCRIPTION SPECIFICATIONS The PRS1 is a versatile, reliable and economical solution to most machine 1. PRIMARY SUPPLY VOLTAGE: Available for 115 or 230 VAC 10%, speed switching problems. It is not affected by overspeeding and will operate in 50/60 Hz 2.5 VA (See Ordering Information). either direction of rotation. 2. SENSOR OUTPUT POWER: +12 VDC 5% regulated, 60 mA max. The heart of the PRS1 is a solid-state CMOS logic circuit, that continuously 3. SIGNAL INPUT CHARACTERISTICS: See PRS1 Input Circuits, measures the elapsed time between successive trailing edges (negative going) of Sensor Connections & Configuration Switch Set-ups section. an incoming pulse train or waveform. It compares this time with an adjustable 4. FREQUENCY RANGES AVAILABLE: Available in 5 ranges, each range set-point reference and determines if the period of the waveform is longer providing a relay pick-up or drop-out adjustment span of 10:1. (See Ordering (underspeed) or shorter (overspeed) than the set-point reference. Information) The internal relay is energized during normal operation and can be set to 5. RELAY CONTACT OUTPUT: FORM C (SPDT) contacts max. rating 5 de-energize on either under or overspeed by a programming switch. The unit amps 120/240 VAC or 28 VDC (resistive load), 1/8 H.P. 120 VAC can be connected for simple over or underspeed detection or for latch/trip-off (inductive load). The operate time is 5 msec nominal and the release time is operation in a machine STOP/START circuit. 3 msec nominal. The PRS1 features built-in hysteresis (differential between pick-up and drop- 6. RELAY LIFE EXPECTANCY: 100,000 cycles at max. rating. (As load out) of 5% of set-point speed. This prevents the output relay from chattering level decreases, life expectancy increases.) when operating at or near the set-point speed. The set-point control is a 20-turn 7. RESPONSE TIME: Response time is equivalent to the period of set-point screwdriver adjustment accessible at the top of the unit with a 10:1 adjustment frequency, plus 5 msec for relay pickup or plus 3 msec for relay dropout. range. An LED indicates when the relay is energized. A built-in +12 VDC 8. OPERATING TEMPERATURE RANGE: 0 to 60C. regulated power supply, furnished power for the internal circuit and for external 9. WEIGHT: PRS1 PLUG-IN MODULE - 8 oz (226.8 g). sensor excitation. The plug-in module mates with a heavy duty, CSA approved base mounting WARNING: SPEED SWITCHES MUST NEVER BE USED AS PRIMARY PROTECTION AGAINST HAZARDOUS OPERATING CONDITIONS. socket with pressure clamp screw terminals that accept stripped wires without Machinery must first be made safe by inherent design, or the installation of lugs. Closed back construction allows mounting directly on metal panel without guards, shields, or other devices to protect personnel in the event of a an insulation barrier. hazardous machine speed condition. Then a speed switch may be installed to help prevent the machine from entering the unsafe speed condition. DIMENSIONS In inches (mm) 13. ERRATIC OR IRREGULAR SHAFT MOTION PRS1 APPLICATIONS Since the PRS1 operates by timing each successive signal cycle, relay chatter The following guidelines and considerations will help to assure the best can be experienced when the set-point speed is adjusted close to the running performance when applying the PRS1 Speed Switch. speed and the motion of the sensor shaft is irregular. For example, if a sensor 1. SENSOR AND FREQUENCY RANGE SELECTION detects teeth of the driven sprocket in a chain drive with a good deal of chain (See PRS1 Sensor & Frequency Range Selection section.) slack, the period between adjacent signal cycles can vary as much as 2:1 as the 2. RESPONSE TIME driven sprocket alternately overhauls and takes up slack. This does not present The PRS1 has an internal adjustable timer whose time-out period is a problem if the set-point is adjusted at 5 or 10% of running speed, but if the determined by the set-point adjustment. In operation, this timer is reset set-point is to be 90% of running speed, the PRS1 output will chatter as the (retriggered) at the start of each signal cycle and the internal logic circuitry chain picks up and gives out slack. Again, the solution to this problem is to monitors whether the signal cycle concludes before time-out occurs locate the sensor at a point in the drive train where the motion is smooth. (overspeed) or if time-out occurs before conclusion of the signal cycle Note: The PRS1 has built-in hysteresis of 5% of set-point speed, i.e. underspeed (underspeed). This operating scheme results in an inherent delay in output output occurs at 95% of the overspeed set-point. This allows a set-point near switching response which is insignificant at moderate and higher frequencies, running speed provided shaft motion is reasonably smooth. but can be appreciable at low frequencies. For example, with the PRS10011 4. OVERSPEED OPERATION AND HI-FREQUENCY SENSOR (Range 0.1 to 1 Hz) set to the minimum range, underspeed output will not DROPOUT occur until 10 sec after the initiation of the last signal cycle. Overspeed All ranges of PRS1 units can be operated in the overspeed condition up response is directly related to the period of the signal frequency and will be through 10 KHz without experiencing operational discontinuities. However, faster, depending on the amount of overspeed. when subject to higher input signal frequencies (12 to 15 KHz), signal roll- The inherent delay at low frequencies can be an advantage when the PRS1 is off will occur in the input circuit and the output will transfer to underspeed applied as a zero-speed switch. However, for fast response, a higher as if the signal had dropped to zero frequency. frequency unit with an appropriate sensor arrangement should be used. This Sensor signal drop-out at high frequencies will also cause a false underspeed can often be accomplished simply by moving the sensor to a higher speed output. Caution is advised when selecting proximity, photo-electric, and other shaft, or by going directly to the drive motor shaft with an ARCJ Ring Sensor sensors that have limited high frequency ratings, to ensure that their maximum Kit. (See Sensor Section of the RLC Catalog.) output frequency limit is not exceeded at maximum machine speed. OPERATING MODES MODE A: LOW SPEED OPERATE, OVERSPEED Internal relay is energized at all speeds below the set-point speed, and de-energizes when speed exceeds the set-point speed. Relay again energizes when speed drops approximately 5% below the set-point speed. MODE B: HIGH SPEED OPERATE, UNDERSPEED DROPOUT Internal relay is de-energized at all speeds below the set- point speed, and energizes when the speed exceeds the set- point. The relay again de-energizes when the speed drops approximately 5% below the set-point. MODE C: LATCH, HIGH SPEED OPERATE, UNDERSPEED DROPOUT Pushing the Start button energizes the internal relay and starts the machine. When operating speed is reached, the relay stays latched with the Start button released. If the machine speed drops below the set-point, the relay unlatches, sounding the alarm and stopping the machine. MODE D: LATCH, LOW SPEED OPERATE, OVERSPEED DROPOUT Pushing the Start button energizes and latches the relay and starts the machine. The relay stays latched as long as machine operates below set-point speed. If the machine exceeds the set-point speed, the relay unlatches, sounding the alarm and stopping the machine. ORDERING INFORMATION PART NUMBERS FOR AVAILABLE SUPPLY VOLTAGES MODEL NO. DESCRIPTION A.C. POWER 0.1-1 Hz 1-10 Hz 10-100 Hz 100-1 KHz 1 K-10 KHz 115 VAC PRS10011 PRS10101 PRS11011 PRS11021 PRS11031 PRS1 Speed Switch 230VAC PRS10012 PRS10102 PRS11012 PRS11022 PRS11032 Socket, 12-Pin 2300200 2