Voith 91868550, Instructions And Operating Manual

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Instruction and Operating Manual
Overspeed Protector CTO-B45202
2019 / 02
J.M. Voith SE & Co. KG │ Division Digital Ventures
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918 3626018864 en D – 74564 Crailsheim Version: 2.1
6.2 Adjustment of UF- and If-potentiometers
Uf-potentiometer (please see Fig. 5)
The Uf-potentiometer is provided to adjust the turbine trip frequency reference, it is set at
the factory and sealed. Any adjustment is prohibited!
If-potentiometer (please see Fig. 5)
This potentiometer needs to be adjusted only if you want to use the actual speed remote
indication. The limit of 20 mA actual speed remote indication is permenantly assigned to
the turbine trip frequency and is corrected automatically on adjustment of the turbine trip
frequency. The initial value of 4 mA is to be assigned to 0 Hz.
On adjustment of the turbine trip frequency (see Chapter 6.1), however, also the
assignment of 4 mA initial value changes at the same time. It is possible to re-adjust this
4 mA initial value to 0 speed by means of the If-potentiometer. To do so, remove the
locking compound of the If-potentiometer and renew it after the adjustment.
For this purpose, the output of the actual speed remote indication is put on an mA-meter.
At 0 speed, the If-potentiometer is turned until the mA-meter indicated 4.0 mA. Turning the
potentiometer clockwise will increase the mA-signal.
In case of a trip of the CTO, the actual speed remote indication returns to 0 mA due to the
external switch-off of the 24V CTO supply. In case this external switch-off of the 24V
supply is prevented erroneously, the actual speed indication increases to higher values and
the allocation of the speed to the actual speed signal is no longer correct during this state.
After a proper reconnection of the CTO, this state eliminates on its own.
T4-potentiometer
(please see Fig. 6 and Fig. 4)
The T4-potentiometer is used to set the trip time of the trip simulation function (partial
stroke test with trip-stop cylinder. The potentiometer is in the VRM and protected by a
cover.

Following the procedure described below, the pressure-tight, explosion protected
enclosure of the VRM will be opened and the explosion protection will no longer be
effective. Therefore, it has to be checked before that there is no explosive atmosphere
or may form as long as cover E is not remounted and secured by screws F.
Loosen the 2 Allan screws F (5 mm width across flats, see Fig. 4) in order to get to the T4-
potentiometer. The remove cover E. On account of the O-ring (see Fig. 1) in cover E it
might be somewhat hard to remove it.

The cylindrical part of the cover and the enclosure bore form part of the pressure-tight
enclosure for explosion protection. The cylindrical surface of the cover and the
associated surface of the enclosure bore must not be damaged. The corrosion
protection of these surfaces needs to be completely preserved!
Fig.: 6