SCHIEBEL SRG2 Series Manual

Positioner SRG 2xx
DS-ENGLISH-SRG2XX-V2.00-2012.07.17
SEC-DS-ENGLISH-SRG2XX-V2.00-2012.07.17
Positioner SRG2xx

1 General

The SRG1xx positioner (see Figure 1) facilitates the control of an electric actuator by
means of a set point with current output 0(4)...20mA. A potentiometer with a resistance
value of 100 to 10k is used as an actual value in the actuator.The position control of
the actuator is carried out using the SRG2xx, i.e. the positioner ensures that the actual
value and thus the position of the actuator follows the set point.
Figure 1: Symbol

2 Operation and electrical connection

The set point current I is conducted via terminal 77 and the current measuring diode to the resistor R . The
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set point I (see Figure 3 and 4) can be measured at the measuring points using a measuring device (internal
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resistance max. 10 )) without impairing operation. The actual value (actuator position) is determined in the
SRG2xx from the position of the actual value potentiometer (connected to the terminals 74 to 76) coupled with
the actuator. This actual value is compared with the set point in the positioner. If both values are equal except
for a residual difference (adjustable with potentiometer D), none of the two relays (K3, K4) on the positioner
picks up (see Figure 2).
Figure 2: Basic wiring diagram
If the set point is larger than the actual value, the K4 relay picks up (the corresponding yellow LED lights), the
actuator must open. If the actual value is larger than the set point, the K3 relay picks up (the corresponding
yellow LED lights), the actuator must close. The control of the motor may be carried out directly via the relays
of the SRG or via an additional reversing starter unit depending on the motor type.
The reference voltage required for control and the BZL reference line are separated galvanically from the
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