Laurel-electronics LTM CTR SERIES PULSE, AC or PROCESS TOTALIZER INPU Uživatelský manuál stáhnout pdf (Strana 25)

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13. DUAL RELAY OPERATION

The optional dual solid state relays can operate in a basic alarm mode, in a hysteresis band mode,

or in a deviation band modes, as explained below. Setpoint operation is referenced to the digital

reading in engineering units that is internal to the transmitter. For example, rate alarm or control

would be referenced to a setpoint in RPM.

Time

1000

Setpoint

OFF OFF

Time

1000

Setpoint

OFF

ONON

Active High Basic Alarm Active Low Basic Alarm

A basic alarm changes state automatically when the reading rises above a specified limit, and

changes back automatically when the reading falls below that limit. A red LED indicates the

relay is in an alarm condition, which can be active high or active low, as programmed.

Time

1050

950

Pass

Fail

Time

1050

Setpoint = 1000

Hysteresis limit = 50

Hysteresis band = 100

Heater

OFF

950

Setpoint = 1000

Deviation limit = 50

Deviation band = 100

Hysteresis band Deviation band

A hysteresis band controls relay action symmetrically around a setpoint. The relay closes (or

opens) when the reading goes above the setpoint plus one hysteresis limit, and opens (or

closes) when the reading falls below the setpoint less one hysteresis limit. A narrow hysteresis

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Laurel-electronics LTM CTR SERIES PULSE, AC or PROCESS TOTALIZER INPU Uživatelský manuál Strana 25