Siemens 7ML19985AB01 Manuel D’Utilisation

RELAYS

Three on board multipurpose relays are provided by the OCM-3. P15, 18 and 21 set
the respective functions for relays 1, 2 and 3. Depending on the function selected,
these parameters determine the need and configuration of the subsequent relay
control parameters, P16, 17 (relay 1); P19, 20 (relay 2) and P22, 23 (relay 3).

If the relay is to function as a driver for a remote totalizer or as a flow sampler contact,
the totalizer multiplier (P32) will be factored by the setpoint . Note that parameters
P16, P19, and P22 will default to zero. When a relay is set to totalizer (P32), you must
have the applicable parameter (P16 for relay 1, P19 for relay 2, or P22 for relay 3) set
to something other than zero (normally 1).

Example: For relay 1

Relay totalizer factor = totalizer factor (P32)

relay 1 setpoint (P16)

= 100 (P32=5)
2 (P16)

= 50 units/pulse

The status of each relay is shown in the display. Refer to \ Flow and Total Display.

mA OUTPUT

The OCM-3 provides a mA output (TB1-4/5) which can be assigned (P24) to
represent the measurement of flow, head, velocity or temperature. The associated
scaling, P25, is factory set to a value of ‘0’. This provides normal scaling with respect
to the assigned measurement.

Normal scaling for representation of flow, head or velocity is:

» 0 or 4 mA = 0

» 20 mA

= maximum measurement value for:

» P6

: flow rate

at maximum head

» P7: maximum head

» P10: velocity
at maximum head

Normal scaling for representation of temperature is:

» 0 or 4 mA = – 40 °C

» 20 mA

= 60 °C

If custom scaling is required, the 20 mA corresponding value (other than 0) can be
entered into P25. The range (0 to 20 or 4 to 20 mA) and damping (see Damping) are
set via P26 and P27 respectively.

For battery operation, have relays energizing on alarm.

7ML19985AB01

OCM III