ADC AD-464 service manual Rtd

5.Hi-Limit Controller

The dryer utilizes six (6) channel controller (HLC-1) to monitor various locations on the dryer for over temperature faults. The hi-limit controller enables the dryer to continually monitor up to six (6) Resistive Temperature Devices (RTD's) at one time. Each channel is individual with set points. The hi-limit controller scans each channel, and in the event of an alarm, the scanning will halt (stop), and the Single-Pole-Double- Throw (SPDT) will change states signaling a fault. The hi-limit controller will remain in alarm until the reset button is pushed and the temperature has fallen below the set-point temperature. The scan rate can be adjusted from 4 to 12-seconds per channel.

•Channel #1 is used to monitor the exhaust for an over temperature situation.

•Channel #2 is used as an over burner monitor (for Gas Models Only).

•Channel #3 is used to monitor intake temperature (for Gas Models Only).

•The remaining channels are spares that can be used for future expansion. a. Hi-Limit Controller Replacement

1)Discontinue electrical service to the dryer.

2)Loosen the four (4) screws hold the hi-limit mounting bracket.

3)Slide the mounting bracket off of the screws through the keyhole.

4)Disconnect the plug going to the hi-limit controller.

Current

Production

5) Remove the two (2) screws holding the mounting slides.	Past
	Production

6) Remove the two (2) slides.

7) To install new hi-limit controller, reverse Step #6 thru Step #2.

8) Reestablish electrical service to the dryer.

HI-LIMIT CONTROLLER TEMPERATURE SPECIFICATIONS

			GAS			STEAM
	ºF	ºC	HI-LIMIT NAME	ºF	ºC	HI-LIMIT NAME
RTD 1	225	107	Exhaust Temp. Limit	225	107	Exhaust Temp. Limit
RTD 2	200	93	Over Burner Temp.	650	343	Intake Temperature
RTD 3	650	343	Intake Temperature	500	260	N/A*
RTD 4	500	260	N/A*	500	260	N/A*
RTD 5	500	260	N/A*	500	260	N/A*
RTD 6	500	260	N/A*	500	260	N/A*

* Not applicable...controller channels must be set to 500º F (260 ºC).

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