
PCM30U, PCM30U-OCH – User's, Operating and Maintenance Manual
E Special 234 mm Modules for Protections
E.1 PBS, 4PBS
E.1.1 Module description
Number of commands: 10 + 1 acknowledge input, 4PBS variant has only 4 commands.
The unit can be equipped with a display to count received and transmitted commands
The unit has integrated central part, real time and battery backed-up storage of command and
alarm log
Improved combined outputs for higher load and speed
A sub-unit for line interface
The unit is supplied in two variants
A channel unit to be put into PCM30U-OCH, 6OCH and 6OCH8 subrack
A self-standing unit as PCM30U-OCH, PWA subrack – must be equipped with interface
submodule.
PBS unit is designed to transmit commands or binary states via PCM30U-OCH equipment. Two units
located at opposite stations ensure highly secure bidirectional transmission of 10 commands / binary states.
Each of 10 inputs with galvanic decoupling has two terminals for the connection of external contacts. A
battery with grounded plus or minus pole can be used to supply bias voltage.
In order to improve interference resistance, inputs 1 - 4 are equipped with circuits guaranteeing low input
impedance up to the threshold voltage; inputs 5 - 10 have constant input impedance.
For each input, the value of external DC voltage can be adjusted individually by jumpers (24 V, 48 V,
110 V or 220 V). Voltage filtering is done by input threshold adjusted to 60 – 75 % of the nominal voltage
level.
There is an internal 24VDC power source included in the unit with the output on minus pole to enable
connection of external unbiased contacts. The current is limited to 40 mA. The external contacts are to be
interconnected with internal source through external cabling.
Each of 10 outputs with galvanic decoupling has two terminals to enable connection of external devices
(e.g. relay windings) with a battery (positive or negative pole grounded) to supply bias voltage.
Outputs 1 - 4 are combined (electronic-mechanical), outputs 5 - 10 are purely electronic.
At the combined outputs, an electronic switch guarantees the speed of switching, while a mechanical
relay makes it possible to have permanent high DC current load even at maximum switched voltage.
Delayed switch-off of the electronic switch prevents arc discharge when the mechanical contacts drop-put.
As a standard, the combined outputs are equipped with switch-on contacts, switch-off contacts can be
supplied on demand (closed when power is off). Maximum load is 4 A/250 V DC.
The advantage of electronic outputs is their speed of switching. Their lifetime period is practically
independent from the number of their working cycles. (They can be used also for slow data transmission at
rates up to 200 Bd.) As a standard, the outputs are equipped with switch-on contacts, switch-off contacts can
be supplied on demand (closed when power is off). Maximum load is 1A /250 V DC.
The functions of logical sum (one of the two inputs must be excited) or logical product (both inputs
excited) can be applied to the command inputs, with the resulting signal being then transferred to both
outputs at the same time. This feature is not accessible with 4PBS variant.
In addition to the command inputs, there is another input (called QUIT) in the unit serving for
acknowledge button. This function can be assigned to a selected output or selected outputs by means of
SW. The selected outputs can then be SW-set to permanent on-state after a command is received. The
attendant must cancel the on-state manually by pushing the acknowledge button.
At each input, time filtering can be set from zero up to 64 ms and prolonged command duration period
up to 10 000 ms. Maximum time duration of the on-state can be limited (by 1 000 ms).
When a failure condition is ascertained in any part of the transmission path, this leads to the command
outputs being blocked in pre-failure states, or optionally to the return to idle state or else to the transmission
of a command with the duration of 150 ms. The failure is shown by the management system and indicated
on the unit itself by means of mechanical and electronic relays. There is always an option to set either
switch-on or switch-off contact by means of a jumper (on when feeding voltage is off).
Power Channel Modules
E-3
446S037.914.14N00