Ct Auxiliary Input (Ammeter) - gefran GFX4 Configuration And Programming Manual

CT AUXILIARY INPUT (Ammeter)

Optional input used to monitor current delivered to the load, both single phase and 3-phase, with automatic recogni-
tion of the internal ammeter transformer.
Models with 4 TA (GFX4-x-x-2-x-x and GFX4-x-x-4-x-x) let you continuously acquire the current values circulating in
the load with sampling interval of 60ms. The current value can be read in variable I.tA1 of each zone. If zone 1 has a 3-phase
load, variables I.tA1, I.tA2 and I.tA3 in the first zone have the current value in line 1, line 2 and line 3, respectively.
You can also read the maximum current value corresponding to running state (ON) in variable I1on. This value is
reset when no power is requested. In 3-phase load configuration, variables I1on, I2on and I3on in the first zone contain the
current value in line 1, line 2 and line 3, respectively.
Models with 1 CT (GFX4-x-x-1-x-x and GFX4-x-x-3-x-x) sample the load current value at a programmable time in-
terval (parameter dG.t). Therefore, you can use the best sampling time for the application being run and, especially, for load
type, since activation of the scan to identify faults on the load with fast systems and short cycle times may be critical for stable
temperature control.
How does the periodic scan work? First, power to all 4 zones is interrupted (control outputs = OFF), then, in succession, if
the power requested exceeds a minimum settable value (dG.P), the individual zones activate to acquire the current value.
If there is current with the 4 zones OFF, the device is in SSR SHORT condition, but the faulty zone is not identified. If no cur-
rent is detected with the zone ON (control output = ON), the device is in NO CURRENT condition, corresponding to a possible
interrupted load or SSR open or no line voltage or blown fuse. If current flows, the sampled value is saved in variable I.tA1.
The 4 ammeter inputs are IN9, IN10, IN11, IN12, and the current value is found in variable ItA1 for zones 1, 2, 3, 4,
respectively.
If diagnostics identifies a fault on the load, the red ER LED starts to flash in sync with yellow LED O1 or O2 or O3 or
O4 for the faulty zone.
The condition POWER_FAULT in OR with the HB alarm can be assigned to an alarm or can be identified in the state of a bit
in the STATUS_INSTRUMENT, STATUS_INSTRUMENT_1, and STATUS_INSTRUMENT_2 variables.
In STATUS_INSTRUMENT_3, you can identify the condition that activated the POWER_FAULT alarm.
The POWER_FAULT diagnostics is configurable with parameter hd.2, with which you can also enable only one of its
parts.
With models that have 4 CTs, you can diagnose the following single conditions:
- SSR SHORT: SSR module in short circuit;
- NO VOLTAGE: no line voltage or fuse blown or load interrupted;
- SSR OPEN: SSR module open ;
- HB: load partially interrupted.
With models that have 1 CT, you can diagnose the following conditions:
- SSR SHORT: SSR module in short circuit;
- NO CURRENT: load interrupted or SSR open or no line voltage or fuse blown;
- HB: load partially interrupted.
For a zone with single-phase load, the default value of the maximum limit or full scale of the current transformer
(H.tA1) depends on the model, and equals 20.0A (30 kW model), 40.0A (60 kW model) or 60.0A (80 kW model). Parameters
for correction of offset (o.tA1) and for the digital filter (Ft.tA) refer to the ammeter input.
If zone 1 has a 3-phase load, the following parameters are significant:
- I.tA1, I.tA2 and I.tA3: ammeter value on line L1, L2 and L3, respectively;
- I.AF1, I.AF2 and I.AF3: filtered ammeter value (see Ft.tA) on line L1, L2 and L3;
- I1on, I2on and I3on: current with control O1 on (ON) on line L1, L2 and L3;
- H.tA1, H.tA2 and H.tA3: maximum limit or full scale of current transformer on line L1, L2 and L3;
- o.tA1, o.tA2 and o.tA3 = offset correction for ammeter input on line L1, L2 and L3;
- Ft.tA = digital filter for ammeter input.
80397M_MSW_GFX4-GFXTERMO4_08-2018_ENG
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