User's manual M244-14L &M244-14M7
2. APPLICATION AND FUNCTIONALITY
M244-14L &M244-14M is a microprocessor based synchronising unit. It is
intended for a phase difference (∆ϕ) measurement between a bus bar and
generator. It can be used in any kind of installation where a manual or semi-
automatic synchronising is required. M244-14 version with LCD can replace
two voltmeters and two frequency-meters. Circular set of 24 LEDs represents
a phase difference. A lit LED displays momentary phase difference ∆ϕ with
a resolution of 20°el. (red LEDs). Within synchronising range ±15°el., the
resolution is increased to 5°el. (green LEDs).
The M244-14M has additional LCD with backlight for a display of a gener-
ator UGEN and bus-bar UBB voltage and both frequencies fGEN and fBB or ∆ϕ.
The M244-14M can replace two voltmeters and two frequency meters, which
are normally part of the synchronising set.
Status output is used to supervise the operation of a microprocessor inside
synchroscope. In case of a microprocessor malfunction the status output
changes state from low to high impedance.
2.1. Operation and synchronising settings
The instrument samples a generator and bus bar voltages using A/D
converter inside a microprocessor. Both voltages are galvanically separated
with measuring transformers. The microprocessor computes voltages,
frequencies and a phase difference between UGEN and UBB. The lit LED in a
circular display represents an actual phase difference from 0° (top position)
to ±180° (bottom position).
LCD (M244-14M only) displays voltages and frequencies or phase angle.
M244 can be supplied from UGEN or UBB. A synchronising relay is activated
when synchronising conditions are set. At the instrument rear side, three po-
tentiometers are provided for adjusting:
Basic synchronising condition settings (normal synchronising mode)
•for setting permitted phase difference ∆ϕ;
•for setting permitted voltage difference ∆U;
•for a delay of synchronising relay switch-on (DELAY).
A synchronising condition is set, when the phase difference and the voltage
difference between UGEN and UBB, for a time of delay, are within the set
limits. The synchronising check relay is then switched on and a SYNC LED
is lit for a preset pulse time (e.g. 100ms, 300ms).
Additional settings are set upon customers request in a factory or by
authorized dealer. Additional settings are set with three jumper switches
inside M244 and/or with a special communication adapter.
WARNING: Only authorized personnel should set additional settings.
For more information, please contact Crompton Instruments support. Review
of all settings is in table 1.
Dead bus bar synchronising
When this function is set, the synchronising relay will be activated and the
SYNC LED will be lit, when the generator voltage exceeds 80% of its
nominal voltage and the bus bar voltage is below allowed UBB voltage noise
level. The allowed UBB voltage noise level is set in factory in range from
10% to 40% of nominal voltage.
8 User's manual M244-14L &M244-14M
