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Relay Outputs
Two configurable relays provide dry contact outputs for a remote totalizer, high/low RATE
alarm, high/low speed alarm, or a calibration weight lifter interlock. The relay contacts are SPST
and should not be used to control more than 250 VA. When a relay is used as a totalizing pulse
relay, limit the frequency of operation to 6 pulses per second for reliable operation. Note that
even though the relays are rated for up to 250 VA, it is highly recommended that electrical noise
emitted from the relays be minimized to assure problem free operation of the processor. When
possible, it is recommended that 24 VDC (10.4 amps max.) be used to drive external loads.
When higher voltage loads need to be driven, it is recommended that an interposing relay be
installed between the WP20 output relay and the load. Two variations of how to wire an
interposing relay are shown in sections 4.12 & 13.
Refer to sections 6.02.27-40 for relay configuration parameters.
4-20 ma RATE current loop output
The WP20 provides four 4-20 ma (or 0-20 ma) current loop outputs proportional to the RATE.
The RATE current loop outputs can be used for driving chart recorders, displays, data loggers,
and similar client provided devices. Use a single shielded twisted pair cable for the current loop
wiring, Belden #8760 or its equivalent is recommended (it can be obtained through
Tecweigh
).
Refer to Sections 6.02.19-23 for the configuration of these current outputs.
WARNING:
THE CURRENT LOOP OUTPUT IS ACTIVE! THAT MEANS A
DC VOLTAGE IS PRESENT AT THE TERMINALS. ENSURE
THAT THE LOOP IS CONNECTED TO A PASSIVE LOAD
(resistive only) OR DAMAGE WILL RESULT!
In most systems applications,
current loop isolation is essential
to eliminate induced noise
interference, and also to eliminate ground loops (when more than one load is in the loop.) The
current loop outputs at the PCB are
non-isolated.
Consequently, the WP20 requires current loop
(signal) isolators for loop isolation (these can be purchased through Tecnetics). Note that if more
than one load is driven by a loop, for proper loop operation, all loads in the loop must be isolated
except the last one. Proper shield grounding is also essential. The maximum load resistance that
can be driven by any single current loop output is 750 ohms, with a maximum voltage of 18.5
Vdc. Refer to the figure in section 4.05 for an example of proper current loop wiring.
HFR output (HFR(4)-CM(10))
The High Frequency Rate (HFR) output provides a square wave signal with a frequency equal to
10 times the calculated RATE. It can be used to drive remote RATE displays and other client
provided devices that are capable of accepting this kind of frequency input signal. The minimum
output frequency is 10 Hz and the HFR max current draw is 60 mA. Refer to Section 7.05.44 for
information on the HFR Damping Parameter, and Section 9.04 for trouble shooting.
HFR Polarity output (POL(2)-CM(10))
The HFR Polarity output outputs approximately 5 Vdc when the RATE is positive and
approximately 0 Vdc when the RATE is
negative
. If the RATE is zero, 5 Vdc will still be
present at the terminals. 5 Vdc will always be present at the terminals in Simulation mode.
Содержание Tecweigh 20
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Страница 10: ... 9 2 09 I O Quick Reference Guide ...
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Страница 24: ... 23 4 03 WY15 and WY25 Scale Wiring load cells ...
Страница 25: ... 24 4 04 HY15 and HY25 Field Wiring ...
Страница 26: ... 25 4 05 WY10 WY10HD and WY20 Scale Wiring LVDTs ...
Страница 27: ... 26 4 06 Chart Recorder Data Logger using the 4 20 ma output ...
Страница 28: ... 27 4 07 Chart Recorder Data Logger using the HFR output ...
Страница 29: ... 28 4 08 Remote Rate Total Display 4 09 Remote Tons Counter ...
Страница 30: ... 29 4 10 Radio Transceivers Local Scale Remote Processor ...
Страница 31: ... 30 4 11 Radio Transceivers Local Processor Remote PLC PC or Remote Display ...
Страница 32: ... 31 4 12 Radio Transceivers Local DC Generator Remote Processor ...
Страница 33: ... 32 4 13 Radio Transceivers Local DC Generator and Processor ...
Страница 34: ... 33 4 14 Multiple Processors to Tecweigh Multi Scale Display MSD ...
Страница 35: ... 34 4 15 Interposing Relay External 120 vac Power 4 16 Interposing Relay Internal 30 vdc Power ...
Страница 61: ... 60 SC300 PCB WY15 and WY25 SC400 PCB WY10 and WY20 ...
Страница 71: ... 70 10 01 WY10 Dimensions CHAPTER 10 DIMENSIONS ...
Страница 72: ... 71 10 02 WY10 HD Heavy Duty Dimensions ...
Страница 73: ... 72 10 03 WY15 Dimensions ...
Страница 74: ... 73 10 04 WY20 Dimensions ...
Страница 75: ... 74 10 05 WY25 Dimensions ...
Страница 76: ... 75 10 06 HY15 and 25 Dimensions ...