plate. Note: Use only NEW 9 Volt alkaline replacement batteries.

 

OPTIONAL ALARM/CONTROL RELAY
(CONNECTION TO THE RELAY)

  CAUTION! DO NOT TOUCH the terminals of the transformer while the unit is connected to the main AC power supply. To avoid the risk of possible electric shock, unplug or disconnect the recording unit from the main power supply before attempting to access the terminals of the relay. If the recorder is installed with the battery back-up option, disconnect the 9 Volt battery to avoid damaging the recorder and draining the battery.

On 6" inch recording units mounted in a metal enclosure, the chart plate on the recorder case is held by four (4) screws. Unscrew and gently remove the chart plate to expose the relay that is mounted to the back of the chart plate. Otherwise, your recording unit will have a hinged chart plate held in place by two (2) screws located in the upper and lower right hand corners of the chart plate. Remove these two screws and open the hinged chart plate. On 8" recording units, there is a single screw along the right hand edge that secures the chart plate inside of the enclosure. Loosen this screw and open the hinged chart plate to expose the relay terminals. If you are not sure how to access the relay terminals of your recording unit, please contact COBEX Recorders before continuing.

The relays that are used in this recording unit are latching type relays. That is, the contacts of the relay will remain either closed or open (even when there is no power applied to the recorder) until the relay is pulsed with a signal from the recorder to change the position of the contacts.

Refer to Figures 2A and 2B for the location of the screw terminal connections for the relays. Note: A RED, BLACK and WHITE set of wires may already be provided as an external connection to the relay's terminal block.

For recorders that are programmed with a single relay set-point, the terminal position NC will be closed when the pen is positioned to the right of the control set-point and will be open when the pen is positioned to the left of the control set-point.

For recorders that are programmed with HI/LOW (or "band" alarm) relay set-points, the terminal position NC will be closed when the pen is positioned in between the control set-points and will be open when the pen is positioned outside of the control set-points.

Refer to the Relay information in the Recorder Specifications section of this manual for the electrical ratings of the relays. Warning: Serious injury or damage to the recording unit may result if the ratings for the relays are exceeded.

 

SETTING THE ALARM/CONTROL
SET-POINT FOR THE RELAY

While the recorder is operating normally (recording temperature or some other variable), press and hold the "change chart" button (#3) for approximately one (1) second until the pen begins to move to the left and then release the button (refer to Figure 5). Wait until the pen has moved onto the pen lift ramp (if available) or near the edge of the chart paper and stops. When the "change chart" button (#3) is pressed again, the pen will begin to move back onto the chart briefly stopping at the outermost graduation of the chart.

The pen arm will then move to the first control set-point position and the green LED light will turn off. The pen will remain at this position for a period of approximately five (5) seconds during which time the control set-point can be adjusted using the left arrow (#1) or the right arrow (#2) push buttons. Refer to the following figure for a diagram of the push buttons. When the time has expired for adjusting the control set-point, the green LED light will turn back on and the unit will begin recording.

When the pen has two control set-points, the pen then moves to the second control set-point at which time the second control set-point may be adjusted. Having


8

R70-32
REV(07/13) E

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