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  <xs:element id="powl_DeferredCompensationArrangementWithIndividualCompensationAdjustmentIncomeExpense" abstract="false" name="DeferredCompensationArrangementWithIndividualCompensationAdjustmentIncomeExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="powl_DefinedBenefitPlanEmployeeCoverageAgeOfIndividual" abstract="false" name="DefinedBenefitPlanEmployeeCoverageAgeOfIndividual" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="powl_DefinedBenefitPlanPlanParticipantRetirementAge" abstract="false" name="DefinedBenefitPlanPlanParticipantRetirementAge" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="powl_TwoThousandFourteenEquityIncentivePlanMember" abstract="true" name="TwoThousandFourteenEquityIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="powl_NonEmployeeDirectorEquityIncentivePlanMember" abstract="true" name="NonEmployeeDirectorEquityIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="powl_TimeBasedRestrictedStockUnitMember" abstract="true" name="TimeBasedRestrictedStockUnitMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="powl_PerformanceBasedRestrictedStockUnitMember" abstract="true" name="PerformanceBasedRestrictedStockUnitMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="powl_ShareBasedCompensationArrangementByShareBasedPaymentAwardAuthorizedPlanExtensionPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAuthorizedPlanExtensionPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="powl_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfActualAmountOfUnitsEarned" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfActualAmountOfUnitsEarned" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="powl_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetRSUGrantedRange" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetRSUGrantedRange" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="powl_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantOtherThanOptionsAndSARs" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantOtherThanOptionsAndSARs" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="powl_ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualSharesIssuable" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualSharesIssuable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="powl_ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualSharesIssuableGrantDateValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualSharesIssuableGrantDateValue" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="powl_NumberOfNonEmployeeDirectors" abstract="false" name="NumberOfNonEmployeeDirectors" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="powl_IrrevocableRabbiTrustMember" abstract="true" name="IrrevocableRabbiTrustMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="powl_ShorttermInvestmentsFairValueDisclosure" abstract="false" name="ShorttermInvestmentsFairValueDisclosure" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="powl_LeaseAssetsAbstract" abstract="true" name="LeaseAssetsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="powl_LeaseLiabilitiesAbstract" abstract="true" name="LeaseLiabilitiesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="powl_ReportableSegmentMember" abstract="true" name="ReportableSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
