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MODEL2000A/MODEL2000B/MODEL2000C/MODEL2000D/MODEL2000E

The 2000 Series "A" Option provides two Form C, 10-A contact relays (250 V-AC) on a plug-in board. The "B" Option board provides two Form A opto-isolated AC/DC solid-state relays rated 120 mA at 125 VAC or 250 mA at 150 VDC.

Both options are available for all models, for applications that require alarms and/or process control. The solid-state version is recommended for high duty cycles and low-level loads.

Either setpoint may be latching or nonlatching. In the latching mode, when an alarm or shutdown condition is reached, the output remains in the alarm condition until reset via front-panel push buttons, the optional serial interface, or a logic signal received at the rear connector. In the nonlatching mode, the output is automatically reset as soon as the alarm condition ceases to occur.

Each relay may be separay configured to be energized above or below the setpoint, or may be disabled. Also, each relay may operate in band deviation or hysteresis mode.

Deviation mode sets up a passband around the setpoint and is often used for component pass-fail testing. In this mode, an alarm is generated whenever the reading is a specified number of counts above or below the setpoint—for example, to flag an out-of-tolerance condition.

In hysteresis mode, the relay is activated at a specified amount above the setpoint and deactivated at the same amount below the setpoint. Hysteresis can be used to extend relay contact life by minimizing relay chatter around a setpoint due to signal noise or feedback from load switching.

Relay action may be derived from the filtered measurement signal, to reduce the chance of alarm triggering due to noise. Or it may be selected to operate from the unfiltered signal, to achieve the fastest response time (typically 17 ms for a Digital Panel Meter with the solid-state relay board).

Relay chatter from signal noise can also be reduced by activating a programmable time delay (1 to 128 readings, corresponding to 20 ms to 2 s) prior to updating the output. Snubber circuitry in the relay board helps prolong contact life. The relay response time of counter meters is controlled by a selectable gate time from 10 ms to 199.99 s.