User guide

RevA MN300282 23of34
ELECTRICAL StepSix
Input Power and Relay Connections:The EchoSwitch® is powered from 95 to 250 VAC power.Power is
appliedtotheL1andL2terminals.Typically,HotisappliedtoL1andNeutraltoL2.TheGndterminalshould
beconnectedtoasolidearthgroundtohelpshieldthesensorfromexternalEMI/RFIinterference.
The EchoSwitch® features three 60 VA, 2A max relays.Relay 1 has both the Normally Open and Normally
Closed contacts available.Relays 2 and 3 have the Normally Open contacts available.All three relays have
theircommonsconnectedandareisolated.TheexamplebelowshowsRelay2wiredNO.Makesuretoselect
arelaystatethatisfail‐safeandtakesintoaccountwhenpowerislosttotheEchoSwitch®.
Theswitchingofheavyinductiveloadssuchaspumpmotorscancreatevoltagespikesinthemanythousands
of volts.It is recommended that the power to the EchoSwitch® and to the coils of the isolation relays be
sourcedfromamainthatisnotswitchinginductiveloadsasshownbelow.
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 Note#1–Isolatepowertoinstrumentfrompowertoload(pumps,etc.)asmuchaspossiblebyrunning
powertothesensordirectlyfrommainpowersource.
RelayConfiguration:
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Allthree(3)EchoSwitch®relayssharethecommonrelayterminal. 
 Relay#1isaForm“C”SPDTcontact.
o It is useful for controlling  a valve which requires a contact to open
andacontacttoclose.
 Relays#2&#3areForm“A”SPSTcontacts.
o These two relays (#2 & #3), in addition to relay #1, can be used for
controllingvalves,pumpsoralarms.
Note:Because all three (3) relays share the common relay terminal, the
relaysmustallswitchthesamepower.
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