The Ampcontrol EFL (Earth Fault Lockout) Protection Relay is a safety device designed to provide earth fault lockout (EFLO) and frozen contactor (FC) protection, compliant with AS/NZS 2081:2011 sections 7 & 9. It is suitable for installation on mining outlets that require these protection functions and is compatible with a wide range of system voltages from 110V up to 1.1kV (barrier dependent). The relay also offers a selectable undervoltage (UV) protection function.
Function Description:
The EFL Relay operates by continuously monitoring the resistance of the phase conductors to earth on the load side of the outlet's main contactor when the contactor is open. If this resistance falls below an acceptable level (tripping threshold), the EFL will initiate an EFLO trip, preventing the outlet from being started. This initial EFLO test, performed when the relay first energises, can take up to 10 seconds to complete as the cable needs to be charged before measurements are taken. If successful, the MCR output relay will energise, provided no latched FC, EFLO, or UV trips are present. EFLO trips are latched and require an external reset via shorting the External Reset terminals, typically with a normally open pushbutton.
The Frozen Contactor (FC) Protection Function addresses both logical and electrical aspects.
- FC (Logical) Protection: This function is triggered by a discrepancy between the position of the main contactor (MC) and its interposing relay. The EFL monitors the MC's position via an auxiliary contact wired to the MCI input and the interposing relay's position via the RUN input. A mismatch indicates the MC is either welded shut (Failed to Open) or frozen open (Failed to Close).
- FC (Electrical) Protection: This monitors the voltage on the load side of the main contactor through the HV barrier. After the contactor opens, the EFL Relay waits for a period (determined by the Back EMF time setting) for the motor's Back EMF to subside. If the measured voltage then exceeds 25Vac or 60Vdc, an FC (Electrical) trip is initiated.
Both logical and electrical FC trips cause the EFL Relay to open its CBR output relay, which should be wired to trip the upstream circuit breaker, removing power from the frozen contactor. FC trips are latched and can only be reset by pressing the FC Trip Reset Button on the relay's fascia, after the fault is investigated and rectified. An FC trip cannot be reset unless the EFL Relay's super-capacitor is charged.
The Undervoltage (UV) Protection Function, if activated, monitors the voltage on the outlet via the HV Barrier. An UV trip is initiated if the measured voltage falls below 50% of the selected system voltage. UV trips are latched and can be cleared by shorting the External Reset terminals. The UV Protection Function can be activated or deactivated via the Voltage Selector Switch on the fascia.
Important Technical Specifications:
- Supply Voltage: 24Vdc ± 20% or 24Vac ± 20%, 50Hz.
- Power Consumption: < 5W.
- System Voltage Compatibility: 110V to 1.1kV (with appropriate barrier).
- EFL Tripping Thresholds:
- 3PH Load Disconnected: Trip by 3MΩ.
- 3PH Load Connected: Trip by 1MΩ.
- Undervoltage Protection: <50% of Voltage setting.
- Relay Contacts:
- MCR Trip Contacts (1 x CO): 250V a.c., 6A, 300VA (AC1), 60VA (AC15); 30V d.c., 1.2A (DC1).
- CBR Trip Contacts (1 x CO): 250V a.c., 6A, 300VA (AC1), 60VA (AC15); 30V d.c., 1.2A (DC1).
- EFLO Indication Contacts (1 x NC): 250V a.c., 6A, 300VA (AC1), 60VA (AC15); 30V d.c., 1.2A (DC1).
- FC Indication Contacts (1 x NC): 250V a.c., 6A, 300VA (AC1), 60VA (AC15); 30V d.c., 1.2A (DC1).
- Dimensions (HxWxD):
- EFL: 111 x 45 x 114mm.
- Barrier: 111 x 22 x 114mm.
- EFL with Internal Barrier: 111 x 75 x 114mm.
- Terminal Max. Wire Gauge: 2.5mm².
- IP Rating: IP20.
- Operating Temperature: -20°C to 60°C.
- Humidity: Between 10% relative humidity and the dew point, non-condensing.
- Air Flow: Must be mounted to allow unrestricted air flow through upper and lower air vents.
Usage Features:
The EFL Relay is available in two configurations: with an internal barrier or as a stand-alone unit with an external barrier. Both are DIN Rail mounted. The external barrier configuration allows the barrier to be installed closer to phase conductors if needed, connecting to the stand-alone EFL Relay via "flying leads" (1.2m long for A, B, & C phases).
The user interface on the fascia includes:
- Voltage Selector Switch: Used to select the system voltage (110V, 415V, 1.1kV) and activate/deactivate UV protection. Selecting a voltage within the white portion of the circle activates UV protection, while selecting from the red side deactivates it.
- Time Selector Switch: Used to set the 'Back EMF timer' duration (1s, 2s, 4s, 6s, 8s, 10s, 15s, 20s). This determines the wait time for Back EMF voltages to subside after the contactor opens before trip conditions are applied.
- RST Pushbutton: Resets latched FC trips. Requires the internal super-capacitor to be charged.
- LED Indicators:
- STATUS LED: ON for Internal Fault, FLASHING for EFL Relay Operating System Healthy.
- LOGICAL LED: ON for FC (Logical) Trip Active, OFF for FC (Logical) Healthy.
- ELEC LED: ON for FC (Electrical) Trip Active, OFF for FC (Electrical) Healthy.
- TRIP LED: OFF for FC Healthy, FLASHING for FC Trip (Logical or Electrical) Active (continues flashing without power).
- UNDER VOLTAGE LED: ON for Undervoltage Trip, OFF for Undervoltage Healthy (or Disabled).
- EFLO STATUS LED: ON for EFLO Trip, FLASHING for EFL Relay Charging Phase Cables during EFLO Test, OFF for EFLO Healthy.
Maintenance Features:
- Inspections: Regular 'routine inspections' by trained personnel are recommended. These include visual checks for physical damage, water/dust ingress, cable condition, and label integrity. Detailed 'hands-on' inspections involve verifying secure mounting, wiring against schematics, and secure electrical connections.
- Service: The EFL Relay and Barrier have no user-serviceable parts. All repairs must be carried out by Ampcontrol only. Any attempt to dismantle or repair the unit voids the product warranty and can compromise safety. Ampcontrol recommends returning the EFL Relay and associated barriers to a registered repair facility for service and inspection every 5 years.
- Functional Tests: Regular functional tests are recommended, typically coinciding with periodic maintenance checks, to cover EFLO, FC, and UV protection functions.
- First Time Use / Extended Storage: The EFL Relay uses an internal super-capacitor for long-term energy storage. After extended storage, this capacitor may dissipate its charge, preventing latched FC trips from being reset. Recharging requires the unit to be connected to an external power source (24Vac or 24Vdc) for 5 minutes. This can be done while installed by energising the control supply or by connecting the relay directly to a 24V supply.
- Disposal: Electronic equipment must not be treated as general waste. Proper disposal is essential to prevent negative environmental consequences.
Need help?
General
To Next Page
