Yokogawa RAGN - Manual (Page 12)

<3. PRODUCT DESCRIPTION>
3-2
IM 01R01B10-00E-E 2nd edition: November 01, 2011-00 All Rights Reserved. Copyright © 2011, Rota Yokogawa
3.2 Bistable inductive ring sensor (Option /GR2 to /GR8)
The ring sensor type RI20 is intended for connection to glass Rotameters. It indicates whether the float is
positioned above or below the sensor.
The float must have ferromagnetic properties (e.g. a PVDF float with iron core).
The device is offered into 3 versions:
Type
Option Diameter of tube Possible float (Yokogawa Code)
RI20-10 G /GR2, /GR6 10mm -PD B_N
RI20-17 K /GR3, /GR7 17mm -PD C_N
RI20-17 G /GR4, /GR8 17mm -PD D_N
The RI20 is bistable, i.e. if the float is below the switch point, current consumption is always < 1 mA and it is
> 2.2 mA, if the float is above the switch point. After power on or after power fail the RI20 shows
I < 1 mA. To find the correct float position the float has to move once through the RI20.
It is intended for connection to a non-bistable isolation-switch amplifier complying with DIN EN 50227
(NAMUR) (e.g. options /Wxx). With its plastic housing and its sealed-in electronic equipment, the RI20
meets the requirements for protection class IP67 and can also be operated safely in aggressive
atmospheres.
The RI20 is maintenance-free.
See chapter 6 "EXPLOSION PROTECTED TYPE INSTRUMENTS”
for devices in ATEX version.
3.3 Magnetic contact (Option /GM1 to /GM5)
The limit switch is mounted to a Rotameter type RAGN, if a magnetic float is used and indicates if the flow
falls below the set limit (MIN-contact) or exceeds the set limit (MAX-contact).
When reaching the switch point the Reed contact with bias by a permanent magnet opens when the float
enters the alarm range. The Reed contact closes when the float leaves the alarm range. Opened or closed
the Reed contact remains because of its bistability in its position no matter how far the float moves away.
Due to the low switch output of the Reed contact (max, 10 VA/(W), max. 0.5 A, max. 230 V AC) a
transformer isolated barrier (e.g. option /Wxx) should be connected to the GM.