Tekron ITR, Руководство пользователя, Страница: 9 / 15

because timing is everything P a g e | 9
LED Indicators
ITRs have two green LEDs: -
PWR : On solidly when the correct power is supplied to the ITR
SIG : Lit when the input signal is at a logic high level. Normally this LED will flicker at a
100Hz rate when an IRIG-B signal is fed to the ITR.
ITR Inputs
Copper Inputs
All ITR types can take a TTL level signal fed into the Input terminals at the top right of the
ITR. The polarity of this driving signal must match that on the ITR label.
Note: The copper input signal can be any TTL signal such as an IRIG-B, or it can be pulsed at
TTL Levels (for example Pulse per second). The current loading at 5V is 2mA maximum.
If the ITR is part of a daisy-chained string of devices, the
LOOP terminals on the Copper ITR
can be used to wire to the next device in the daisy-chain. For the other ITR types, both the
incoming and outgoing IRIG-B signals can be wired to the same
Input terminals.
It the ITR is the last device in the daisy-chain, then the
TERM connections can be shorted
which will terminate the incoming IRIG-B signal with 120 Ω . This will correctly terminate a
120 Ω balanced line recommended for signal distribution.
The input to earth isolation is 3.5kV minimum.
The ITR is designed with balanced inputs and outputs which allow the use of twisted pair
cabling to distribute time synchronization signals and provide excellent noise immunity from
induced voltages in the noisy substation environment.
Fiber Inputs
The Fiber ITR types can take both a TTL copper input as well as a Fiber input signal. These
two signal sources are fed to a logic AND gate. The output of this AND gate is then used to
generate the ITR's Fiber signal and the Isolated copper output signals.
If both the copper and fiber inputs are used, the output is therefore the logical AND of the
two input signals. Usually only one input is used at a time, or the two inputs need to be
identical for meaningful outputs.
The fibre connection is ST Fiber,
62.5/125 um, λ = 820 nm, multi -mode. The receiver
sensitivity is -34.4 dBm.