GE L90 Instruction Manual page 76

3.3 L90 CHANNEL COMMUNICATION
For the Internal Timing Mode, the system clock is generated internally. Therefore, the timing switch selection should be
Internal Timing for Relay 1 and Loop Timed for Relay 2. There must be only one timing source configured.
For the Looped Timing Mode, the system clock is derived from the received line signal. Therefore, the timing selection
should be in Loop Timing Mode for connections to higher order systems.
The C37.94 communications module cover removal procedure is as follows:
1. Remove the C37.94 module (76 or 77):
The ejector/inserter clips located at the top and at the bottom of each module, must be pulled simultaneously in order
to release the module for removal. Before performing this action, control power must be removed from the relay.
The original location of the module should be recorded to help ensure that the same or replacement module is inserted
into the correct slot.
2. Remove the module cover screw.
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3. Remove the top cover by sliding it towards the rear and then lift it upwards.
4. Set the Timing Selection Switches (Channel 1, Channel 2) to the desired timing modes (see description above).
5. Replace the top cover and the cover screw.
6. Re-insert the C37.94 module Take care to ensure that the correct module type is inserted into the correct slot posi-
tion. The ejector/inserter clips located at the top and at the bottom of each module must be in the disengaged position
as the module is smoothly inserted into the slot. Once the clips have cleared the raised edge of the chassis, engage
the clips simultaneously. When the clips have locked into position, the module will be fully inserted.
3-30
Figure 3–33: C37.94 TIMING SELECTION SWITCH SETTING
L90 Line Differential Relay
3 HARDWARE
GE Multilin