Heater Catalog - Watlow

SPSTP1 L1Thermostats and AccessoriesBulb and CapillaryTechnical InformationSingle Phase - InterconnectedSingle Phase - InterconnectedSPST1 L11 L2P1 L2Single Phase - Pilot DutyThree Phase Delta - InterconnectedDPSTThree Phase 1 L1Delta - InterconnectedP DPST1 L11 L2P1 L3 1 L21 L3Three Phase Delta - Pilot DutyApplication HintsSingle Phase - Pilot Duty1 L1• Locate the thermostat where ambient temperaturesdo not exceed 150°F (65°C).1 L11 L2• Mount the thermostat in an enclosure that iscompatible with the surrounding environment.SPST• Immerse the entire sensing 1 L2 bulb in the media beingheated.120VÅ(ac)• Make sure the sensing bulb is mounted SPST away from theheating element(s) to negate any undue influence onthe sensing bulb’s temperature 120VÅ(ac) “reading.”P• Keep the capillary tube insulated from electricalconnections.Single Phase - Interconnected• Do not use a thermostat for high-accuracytemperature sensing. Use an appropriateDPST1 L1thermocouple, RTD or thermistor and temperaturePcontrol.Single Phase - Interconnected• Do not use thermostats as a primary power switchingDPST1 L1device. Use a disconnect switch or circuit breaker to1 L2cut power when servicing.P• Interconnect the thermostat to the heater only if:- The heater has one circuit1 L2- The heater’s ampere draw is lower than thethermostat’s rated ampacity at prescribed voltage.• Interconnect either aSinglesingle-Phaseor-double-poleInterconnectedthermostatwith a single-phase heater when the supply voltagedoes not exceed 250VAC for SPST SPST or 480VAC1 L1for DPST.• Only interconnect three-phase P delta heaters to DPSTthermostats.1 L2• Use a single-pole thermostat for pilot duty where thethermostat is not interconnected with the heater, orheater exceeds the volt/amp rating.Pilot Duty WiringSPST, 1-phase1 L1Single Phase - Pilot Duty1 L1PThree Phase Delta - InterconnectedSingle 120VÅ(ac) Phase120VÅ(ac)- Interconnected PDPST1 L11 L3Pilot Duty Three Wiring 1 L1 Phase Delta (Continued)- Pilot DutySPST, 3-phase delta1 L31 L11 L31 L31 L11 L21 L1P1 L1Three Phase Delta - Pilot 1 L1 Duty1 L2120VÅ(ac)SPSTThree Phase Wye - Pilot Duty1 L21 L3SPST, 3-phase wye1 L2120VÅ(ac)SPSTSPSTThree Phase Wye - Pilot Duty1 L11 L21 L2120VÅ(ac)Interconnected WiringSPST, 1-phaseDPST, 1-phasePSPSTSPST1 L2Single Phase - InterconnectedSingle Phase - Pilot DutySingle Phase - Interconnected1 L11 L2PSingle Phase - Pilot DutyPSPSTPPPDPSTPSPSTThree Phase1 L11 L31 L11Three Phase1 L21 L31 L2120VÅ(ac)1 L3Single Phase - InterconnectedSPSTSPST1 L1PP1 L21 L1 Three Phase Delta - InterconnectedDPST, 3-phase deltaDPST1 L1 SPST1 L2120VÅ(ac)PP 1 L21 L11 L31 L21 L3SPSTWATLOW ®Single Phase - Interconnected120VÅ(ac)Three Phase Wye - Pilot DutyP535120V