SECTION 8: FIELD COMMISSIONING
CAUTION
PROCEDURE TO PREVENT POTENTIAL RELAY MISOPERATION
Several test procedures in this section require the application of test currents to the 9300 relay. When
the AC line current is above 1 amp, the 9300 relay is capable of compensating for unequal channel
delay times between the transmit and receive communication paths. This DML (Delay Measurement
Based on Load Current) technique is described in paragraph 2.7.8 of this manual. DML is only en-
abled in two-terminal line applications, and when the line current is above 1 amp. When the 9300 util-
izes DML, the adjusted channel delay compensation time is maintained, even after the line current
drops below 1 amp. This delay compensation value is maintained until the 9300 detects a loss of
communications, excessive BER, or a change in the channel delay as measured by ping pong.
During the commissioning testing, as varying test currents are applied to relays, the relay may enable
this DML feature. To insure the relay does not inadvertently maintain an incorrect value of channel de-
lay compensation, it is recommended that when testing has been completed, the relay power supply
be turned on and off. This will force the relay to reinitiate, and establish a new channel delay compen-
sation value. It is also recommended at this time, that all relay settings be reconfirmed, and recorded
as the “As Left Condition”.
RFL 9300 RFL Electronics Inc.
October 20, 2004 8 - 1 (973) 334-3100
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