Hach 900 MAX manual Alarm Relays, Section, Calibration with the Meter in the Loop

Section 6

7.Press any key to set the output to 20.00 mA dc.

8.Measure the current on the selected output using the multimeter and enter the measured value using the numeric keypad. Press ACCEPT to complete the calibration.

By entering the measured current values, the microprocessor will electronically adjust the outputs to compensate for the difference between the measured values and the expected values.

Figure 24 Calibration with the Meter in the Loop

	Chart	Multimeter
Recorder			900 MAX

Current Loop

Figure 25 Calibration with the 4–20 mA Device Disconnected from the Loop

Multimeter

900 MAX

6.4 Alarm Relays

Note: Current to the relay contacts must be limited to 5 amps. A means to remove power from the relays locally in case of an emergency or for servicing the product must be provided by the user. This can be accomplished with an external switch and a 5-amp fuse or with a switched 5-amp circuit breaker.

Four alarm relay outputs are available as a factory installed option. The relays are mounted in an external NEMA 4X enclosure for installation to a wall or panel. Alarm contacts are rated for 10 amps at 240 V ac (resistive load).

The alarm wiring can be sized according to the load being used. The relay connector will accept wire sizes from 18–12 AWG with a rating of 300 V, 80 °C minimum. Do not use wire smaller than 18 AWG.

For relay pin assignments refer to Table 17 and Figure 26.

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8990cm.fm	Alarm Relays