GE L90 Instruction Manual page 99

3 HARDWARE
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 C37.94SM communications module cover removal procedure is as follows:
1. Remove the C37.94SM module (modules 2A or 2B):
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.
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 C37.94SM module. Take care to ensure that the correct module type is inserted into the correct slot
position. The ejector/inserter clips located at the top and at the bottom of each module must be in the disengaged posi-
tion 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.
Figure 3–42: C37.94SM TIMING SELECTION SWITCH SETTING
GE Multilin L90 Line Current Differential System
3.3 PILOT CHANNEL COMMUNICATIONS
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