GE N60 Instruction Manual page 88

DIRECT INPUT AND OUTPUT COMMUNICATIONS
For the internal timing mode, the system clock is generated internally. Therefore, set the timing switch selection to 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, set the timing selection to
loop timing mode for connections to higher order systems.
The IEEE C37.94 communications module cover removal procedure is as follows:
1. With power to the relay off, remove the IEEE C37.94 module (type 2G, 2H, 2I, 2J, 76, or 77 module) as follows. Record
the original location of the module to help ensure that the same or replacement module is inserted into the correct
slot.
2. Simultaneously pull the ejector/inserter clips located at the top and bottom of each module in order to release the
module for removal.
3. Remove the module cover screw.
4. Remove the top cover by sliding it towards the rear and then lift it upwards.
3
5. Set the timing selection switches (channels 1 and 2) to the required timing modes (see description earlier).
6. Replace the top cover and the cover screw.
7. Re-insert the IEEE C37.94 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
position as the module is inserted smoothly 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 is inserted fully.
Modules shipped since January 2012 have status LEDs that indicate the status of the DIP switches, as shown in the
following figure.
3-42
Figure 3-49: IEEE C37.94 timing selection switch setting
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
CHAPTER 3: INSTALLATION