Socomec TCA21 Current Transformers - 200A/5A or 250A/5A - Class 0,5 - 2,5VA - Ø21mm

Socomec TCA21 200A/5A and 250A/5A Current Transformers - High accuracy measurement class 0.5

Socomec TCA21 current transformers are professional measuring transducers designed to convert high primary currents (200A or 250A) into a standardised secondary current of 5A, suitable for DIRIS dataloggers, COUNTIS energy meters and monitoring systems. Available in two ratings (200A/5A and 250A/5A), they offer an accuracy class of 0.5 and an apparent power rating of 2.5VA, guaranteeing highly accurate measurement for your photovoltaic, tertiary and industrial installations.

A product with multiple variations

This product data sheet covers two models in the TCA21 range:

• TCA21 200A/5A (ref. 192T2020): 20-45 kW installations
• TCA21 250A/5A (ref. 192T2024): 25-60 kW installations

Both models share the same characteristics (class 0.5, 2.5VA, Ø21mm, DIN rail) and differ only in their primary rating.

Why use a current transformer in your installations?

Current transformers are essential for measuring high currents safely and accurately:

• Protection of measuring equipment: enables currents of up to 200-250A to be measured with equipment calibrated for 5A only
• Signal standardisation: standardised 5A output compatible with all dataloggers and energy meters
• Galvanic isolation: electrical separation between power circuit (primary) and measurement circuit (secondary) for maximum safety
• Cost-saving: avoids the use of expensive, heat-dissipating resistive shunts
• Standards compliance: meets IEC 61869-2 standards for energy metering and billing

Typical applications for Socomec TCA21 transformers

• Residential and tertiary photovoltaic installations: solar production measurement (AC single-phase or three-phase inverter side)
• Energy metering and billing: integration with MID meters for consumption/production monitoring
• DIRIS Socomec measurement centres: collection of electrical data (current, power, power factor, harmonics)
• Low-voltage switchboards: monitoring of main feeders and critical circuits
• EV charging stations: metering of energy delivered to high-power electric vehicles (22 kW three-phase)
• Heat pumps and large consumers: real-time consumption monitoring (15-25 kW heat pumps)
• Commercial and industrial buildings: energy management, consumption drift detection, tariff optimisation, etc.

Technical specifications

Why choose Socomec TCA21 200A/5A and 250A/5A transformers?

1. Accuracy class 0.5: high-precision commercial metering and monitoring

Accuracy class 0.5 means that the measurement error is less than or equal to 0.5% in the current range 5%-120% In :

• ✅ Commercial metering and billing: complies with fiscal metering and energy billing requirements (class 0.5 accepted for commercial metering according to IEC 62052-11)
• ✅ High accuracy photovoltaic monitoring: ±0.5% error on 200-250A = ±1-1.25A = ±230-290W @ 230V, very low vs. weather variations
• ✅ Demanding energy management: fine detection of consumption drifts, precise tariff optimisation
• ✅ Reliable reporting: usable data for financial and technical analyses

Comparative table of accuracy classes

Classe	Erreur max	Application typique	Surcoût
0,2S	≤ 0,2%	Comptage fiscal haute précision	+80-120%
0,5	≤ 0,5%	Comptage commercial, monitoring PV précis ✅	Référence
1	≤ 1%	Comptage industriel standard, monitoring PV	-30%
3	≤ 3%	Protection, indication approximative	-50%

TCA21 class 0.5: excellent accuracy/price ratio for professional photovoltaic installations.

2. Apparent power 2.5VA: optimised for compact installations

The nominal apparent secondary power (Sn = 2.5VA) defines the maximum load supported by the CT:

• Maximum secondary load: Z_max = Sn / Is² = 2.5 / 5² = 0.10 Ω
• Compatible with compact dataloggers: typical input impedance 0.01-0.05 Ω (DIRIS Digiware, COUNTIS E)
• Acceptable secondary cable length: up to 30-40m in 2.5 mm² copper (linear resistance 7 mΩ/m)
• Installation close to the panel: 2.5VA suitable for configurations where the CT and control unit are close together (< 20m)

Comparison TCA21 (2.5VA) vs TCA22 (3.75VA)

Modèle	Sn	Z max	Longueur câble max (2,5mm²)	Usage recommandé
TCA21 (Ø21mm)	2,5 VA	0,10 Ω	30-40m	Installation compacte, TC proche tableau ✅
TCA22 (Ø22,5mm)	3,75 VA	0,15 Ω	50-60m	Installation étendue, TC éloigné tableau

Choice: If distance between CT and power station < 20m → TCA21 (more compact, less expensive). If > 30m → TCA22.

3. Two ratings suitable for power ratings of 20-60 kW

TCA21 200A/5A: 20-45 kW installations

• Single-phase PV inverters: 15-20 kW (max current 65-87A @ 230V)
• Three-phase PV inverters: 30-45 kW (max current per phase 43-65A @ 400V)
• Three-phase EV charging stations: 22 kW (current 32A per phase → comfortable margin)
• Commercial heat pumps: 15-20 kW electric

TCA21 250A/5A: 25-60 kW installations

• High-power single-phase PV inverters: 25-30 kW (max current 109-130A @ 230V)
• Three-phase PV inverters: 40-60 kW (max current per phase 58-87A @ 400V)
• Residential/tertiary switchboard feeders: circuits up to 60 kW
• Distributed generation units: cogeneration, generators, etc.

4. FS 5 overcurrent limiting factor: robustness against overloads

FS 5 guarantees that the CT withstands currents of up to 5 x In for 1 second without degradation:

• ✅ TCA21 200A/5A: withstands 1000A peak without destruction
• ✅ TCA21 250A/5A: withstands 1250A peak without destruction
• ✅ Mains short-circuit protection: typical fault current 500-2000A absorbed without destruction
• ✅ Transient overloads: motor starting, transformer inrush, inrush currents.

5. 21mm opening diameter: medium-section cables and bars

The21mm bore allows the passage of :

• Single-phase cables: up to 50-70 mm² (phase output single-phase PV inverter 8-15 kW)
• Three-phase cables: 1 phase of 4G10 to 4G25 mm² cable (PAC 15-20 kW power supply, VE 22 kW terminal)
• Copper bars: cross-section up to 15x5mm or 12x8mm (LV panel, compact connection)

⚠️ Difference TCA21 (Ø21mm) vs TCA22 (Ø22.5mm)

• TCA21 Ø21mm: cables ≤ 70 mm², bars ≤ 15x5mm → standard residential/tertiary installations ✅
• TCA22 Ø22.5mm: cables ≤ 95 mm², bars ≤ 20x5mm → high power installations (> 30 kW single, > 60 kW three)

6. Snap-on DIN rail mounting: rapid installation

TCA21s offer two mounting modes:

• Clip-on 35mm DIN rail: tool-free installation/removal in 5 seconds
• Screw mounting brackets: mounting on base plate or enclosure wall

7. Socomec French manufacturing: quality and reliability

Socomec, founded in 1922 and based in Benfeld (Alsace, France), is a European leader in low-voltage electrical equipment:

• 100% French manufacturing: ISO 9001 certified factory, rigorous quality control
• Recognised expertise: over 100 years' experience in electrical measurement
• Comprehensive range: current transformers from 5A to 5000A, all accuracy classes (0.2S to 3)
• Technical support: full documentation, assistance available

Installation and sizing

Sizing according to installation power

💡Sizing rule: choose CT with In ≥ 1.2 x rated installation current for safety margin and compliance with permanent overload 1.2 In.

Example: Three-phase inverter 50 kW → Current per phase = 50,000 / (√3 × 400) = 72A → Choose TCA21 200A/5A (200A ≥ 1.2 × 72A = 86.4A ✅)

Critical installation rules

⚠️ Critical rule: never leave the secondary open

If the secondary is disconnected on load (open circuit), the CT behaves like a step-up transformer:

• Secondary overvoltage of up to several kV (danger of electrocution)
• Destructive heating of the magnetic core (saturation)
• Destruction of the transformer

✅ Solution: double short-circuit terminals

TCA21s have terminals enabling the secondary to be short-circuited before disconnection, eliminating any risk.

Checking and maintenance

• Initial visual check: check secondary terminals for tightness (torque 0.8 N.m recommended), absence of bore damage
• Secondary continuity test: measure S1-S2 resistance (typical 0.4-1.5 Ω depending on model), value > 10 Ω = internal disconnection
• Annual check: check terminal tightness, absence of abnormal heating, clean if dusty environment
• Periodic calibration: for tax/commercial metering, accuracy class check every 5-10 years (accredited laboratory)

Integration into the Wattuneed ecosystem

Socomec TCA21 transformers integrate perfectly with Wattuneed monitoring and energy management solutions:

• Photovoltaic production monitoring: precise measurement of output from 15-60 kW single-phase or three-phase inverters
• Metering of self-consumed energy: calculation of self-consumption rate, grid injection, etc.
• Energy management system (EMS ): real-time data to control loads (DHW tanks, EV terminals, batteries)
• Anomaly detection: monitoring of consumption drift, identification of malfunctions, etc.
• Tariff optimisation: monitoring of peak/off-peak consumption, red day shaving, etc.
• Reporting and compliance: reports for energy audits, certification (ISO 50001), etc.

In summary: your benefits with Socomec TCA21 CTs

• ✅ Accuracy class 0.5: highly accurate measurement ±0.5%, high performance commercial metering and PV monitoring
• ✅ Two ratings available: 200A/5A (20-45 kW) or 250A/5A (25-60 kW)
• ✅ 2 .5VA apparent power: compatible with DIRIS, COUNTIS power stations, compact installation
• ✅ FS 5 overcurrent factor: supports 1000-1250A peak without degradation
• ✅ Ø21mm bore: 50-70 mm² cables or 15x5mm copper bars
• ✅ S nap-on DIN rail mounting: quick installation without tools
• ✅ Enhanced safety: double short-circuit terminals, 3 kV insulation
• ✅ So comec French manufacturing: quality, durability, technical support
• ✅ IEC 61869-2 standards: commercial metering and billing compliance

Turn your photovoltaic installation into an intelligent production plant with the high-precision monitoring of Socomec TCA21 current transformers.

Wattuneed, your partner for measured and optimised photovoltaic installations.