Snubber Use For Relay - Presys DCY-2050 Manual

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(*) In the case of input under a voltage from 0 to 10V the second factory supplied jumper
should be stored by the user away from the instrument or simply engaged to one of the
connector pins, in a dummy position as illustrated on figure 34.
Fig. 34 - Jumpers on dummy positions for a 0 to 10V input

4.3 - Snubber use for relay

Relay modules are provided with circuits for eliminating electrical arch (RC
snubber). The snubbers are put in parallel with the relay contacts, by placing the jumpers
J1 and J2. When the jumpers are not placed, the relay contacts are kept without
snubbers. The relay module is sent from factory with the jumpers placed.
Note the position of the jumpers in the following figure. The jumpers may be
localized on the front or the back side of the board, depending on its version.
Fig. 35 - Jumpers for selection of snubbers on the relay board
Alarm and control relays are extremely critical in control and safety of industrial
processes. In order to ensure the expected relay behavior, consider the following two
loading conditions.
• High currents circulating through the relay contacts (from 20mA to 3A). When the
relay switches high currents there is the occurrence of electrical arch which damage
quickly the relay contacts. Besides, electrical noise is generated. In these conditions, it is
recommended to use the RC snubbers which come with the relay module (placed
jumpers).
• Low currents circulating through the relay contacts (less than 20mA). The relays could
not function properly when the jumpers are placed. In this case, the snubbers maintain a
4.5mAac/9.0mAac current when connected to a 120VAC/220VAC circuit. This current is
enough, in certain cases, to power a horn or alarm lamps, preventing their deactivation.
In this situation, there is no need to use the snubbers and the jumpers must be removed.
DCY-2050 and DCY-2051
Jumpers 1 and 2
Maintenance
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