ST570S+EIO+E2DP+EHD-2 Motor Protection Controller with Power Dip Retention Module

The ST570S+EIO+E2DP+EHD-2 is a fully integrated motor protection controller system combining the ST570S base unit with expansion I/O module (EIO), dual-power expansion module (E2DP), and power dip retention module (EHD-2). Designed for low-voltage motors at rated frequencies of 50/60Hz and voltages up to AC660V/AC690V, this modular system delivers comprehensive protection, measurement, control, management, and communication — the ideal terminal unit for intelligent MCC or DCS systems.

Key Features

• Complete modular system: base module + EIO expansion + E2DP dual-power module + EHD-2 power dip retention module
• Power dip retention capability — maintains motor operation during momentary voltage dips
• Compact structure, fits directly into 1/4 modular and larger drawer cabinets
• Compatible with contactors, soft starters, VFDs, and circuit breakers
• Suitable for explosive environments (increased safety type "e" per GB/T 3836.3-2021)
• Wide industry application: power generation, oil & gas, petrochemical, metallurgy, coal, paper, rail transit

Compliance Standards

• GB/T 14048.4 — Low-voltage switchgear and controlgear
• GB/T 14598.303 — Digital motor comprehensive protection general technical requirements
• GB/T 3836.3-2021 — Explosive atmospheres, increased safety type "e"

Technical Specifications

Environmental Conditions

• Operating Temperature: -10°C to +55°C
• Storage Temperature: -25°C to +70°C
• Relative Humidity: 5%–95% (no condensation or icing)
• Atmospheric Pressure: 80–110 kPa
• Altitude: <3,000 m
• Pollution Degree: Class 3
• Body Protection: IP20 | Panel Protection: IP54

Auxiliary Power Supply

• Voltage Range: 85–264VAC/50Hz; 110VDC / 220VDC
• Power Consumption: <5W / 10VA
• Surge Current: <20A
• Power Interruption Tolerance: ≥500ms

Current Circuit

• Rated Parameters: 1A (0.2–1A), 5A (0.5–5A), 25A (2.5–25A), 100A (10–100A), 160A (16–160A), 400A (40–400A)
• External CT options for motors >400A: 500A (150–500A), 820A (250–820A)
• Overload Capacity: 2× rated current continuous; 10× rated current for 10s; 40× rated current for 1s
• Rated Frequency: 50/60Hz

Voltage Circuit

• Rated Parameters: 380V, 660V
• Overload Capacity: 1.2× rated voltage continuous; 1.4× rated voltage for 10s
• Power Consumption: <1VA/phase
• Rated Frequency: 50/60Hz

Protection Functions

Thermal Overload Protection

Prevents motor damage from overload-induced overheating. Accounts for both positive and negative sequence current heating effects using inverse-time characteristics. Two reset modes available: Auto Reset (clears fault automatically once thermal capacity drops below threshold) and Manual Reset (requires operator intervention before motor restart).

Blocking (Stall) Protection

Protects against sudden current surge caused by rotor stall during operation. Activates after motor start using maximum phase current vs. rated current ratio; executes in definite-time mode.

tE Time Protection

Compliant with GB/T 3836.3 for increased-safety explosion-proof motors. Monitors the time from locked-rotor current onset to temperature limit — trip setpoint tETrip must satisfy tETrip ≤ tE.

Start Overtime Protection

Prevents insulation damage from prolonged starting. Triggers if current exceeds the set value after the configured start time has elapsed; automatically disengages once the motor enters normal running state.

Single-Phase Earth Fault Protection

Calculates earth fault current from the vector sum of three-phase currents — no additional earth CT required. Effective in low-voltage TN distribution systems. Trip target selectable: contactor or circuit breaker.

Residual Current Protection

Requires external zero-sequence CT. Detects insulation degradation or indirect earth faults. Configurable start-up blocking time; trip target selectable: contactor or circuit breaker.

Current Phase Loss Protection

Monitors three-phase current imbalance after motor start. Triggers when maximum imbalance exceeds 80%.

Current Imbalance & Reverse Phase Sequence Protection

Triggers when current imbalance exceeds the set value (with average current >25%). Reverse phase sequence detected within 200ms after motor start.

Underload Protection

Detects abnormal low-load conditions (e.g., pump cavitation, broken conveyor belt). Monitors current or power; triggers in definite-time mode when below set threshold.

Undervoltage Protection

Triggers when maximum line voltage drops below set value. Includes undervoltage ready function for standby state monitoring.

Overvoltage Protection

Triggers when maximum line voltage exceeds set value to protect motor insulation from high-voltage operation.

Voltage Imbalance & Reverse Phase Sequence Protection

Monitors three-phase voltage imbalance after motor start (effective when average voltage >25%). Reverse phase sequence detected within 200ms.

External Fault Protection

Accepts external digital input signals for fast protection, process interlock, or circuit breaker trip alarm functions. Configurable for trip or alarm output.

Contactor Fault Protection

If motor remains energized 500ms after a protection trip, the system escalates to circuit breaker trip.

Overflow Protection

When fault current exceeds the contactor's rated breaking capacity, the system bypasses the contactor and directly trips the circuit breaker, followed by contactor trip after 200ms.

PT Wire Break Alarm

Activates when any phase current exceeds 25% of rated value and positive-sequence voltage drops below or negative-sequence voltage rises above the PT wire break threshold.