Walchem WDT400 Series Instruction Manual

Walchem WDT400 Series Instruction Manual Manual pdf 35 page image

7.4 Procedure for checking relay outputsIf any prewired output is not activating the device (pump, valve, etc.) attached to it:Verify that the pump or valve is not faulty by plugging it directly into a wall socket.In some controllers, certain relays are NOT internally powered. Check the instruction manual todetermine if the relay is a dry contact type. If so, make sure that external power (115 VAC) has beenconnected to the relay. In most cases, this will be a jumper wire from the large screw labeled “HOT” toone of the relay terminals.Manually activate the relay using the hand-off-auto menu. Verify that the LED on the front panel lightsup. If the device turns on, there must be a problem with the set points if the device doesn’t turn on whenit should.With power removed, check the wiring of the pigtail to the terminal strips. Make sure that they are notloose, that they are not connected by the wire’s jacket, and that they are connected to the correctterminal. Also check the removable terminal block where the black (hot) wires attach (TB2) to see if ithas pulled loose. Restore power and manually activate the relay.With power removed, remove the terminal block that has the black (hot) wires from all of the pigtails(TB2). This simply pulls up off some metal pins. Check these pins for corrosion. If they seem coatedwith anything, scrape off the coating by replacing and removing the terminal block several times.Restore power and manually activate the relay.With power removed, remove the TB2 terminal block again, and attach one lead of a multimeter to thepin that lines up with the wire for the relay in question, and the other lead on the other side of the relay(this will be an adjacent pin for a dry contact relay, or neutral at TB3 for a powered relay). Set the meterto read resistance. Restore power and verify that the meter reads infinite ohms with the relay off (open)and very low ohms with the relay on (closed). If it always reads infinite ohms, the controller is faulty.8.0 SERVICE POLICYThe WDT series Cooling Tower Conductivity Controller has a 2-year warranty on electroniccomponents and a 1-year warranty on mechanical parts (keypad, terminal strip and relays).We stock circuit boards for immediate exchange after we have isolated the cause of the problem.Factory authorized repairs that are received by next-day-air will be returned within 24 hours. Normalpriority for returns is two weeks.Out of warranty repairs or circuit board exchanges are done on a flat fee basis after the warranty isexpired.32

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