Data Flow Systems TCU800, Installation And Operation Manual

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S e t u p
Using Snubbers When Connecting Alarm Outputs
For AC applications, we recommend an RC snubber (DFS # 007-0084) using a 0.1uF capacitor in series with a 47 Ω ½ W
resistor, such as that manufactured by RED LION (Model # SNUB0000).
For DC applications, we recommend a power diode (DFS # 006-0019) with a minimum 3 A 100 peak inverse voltage (PIV)
fast acting rating, such as the industry standard 1N4004 (DIGIKEY # 1N4004CT-ND).
Snubber in AC Alarm Output Application
DC polarity is important. The diode must be connected in reverse bias across the coil terminals or as close
as is practical. That is, the cathode (the side with the white band on the diode body) must be connected to
the (+) supply power and the anode connected to the (-) supply power. Most DC relays do not have a polarity
requirement on their coils, so you must trace out the polarity or use a Voltmeter. Remember that the inductive
transient is a reverse voltage, which causes the diode to conduct and short out the voltage.
Phase Monitor
Single Phase Option (240 VAC only)
The single-phase 240 VAC connection is to the TCU’s A and B phase inputs only. The C phase input must not be connected.
A phase sequence/phase voltage fault will occur if the TCU is configured for single-phase and the C phase is connected.
When configured for single-phase, the TCU’s phase monitor detects phase voltage failures and displays phase A-B readings
only.
Snubber in DC Alarm Output Application