A weighing and safety protection system is a system that collects, monitors, and processes the current and voltage values of the hoisting mechanism during the loading and unloading operations of a grab crane; it performs material weighing and overload safety protection, while also recording, storing, and managing load weight data.
To fill the gap in specialized industry standards regarding weighing safety for grab cranes, the industry standard JT/T 1577-2026, *Technical Requirements for Weighing Safety Protection Systems of Grab Cranes*, has been introduced. Drafted by experts from 13 organizations-including the Research Institute of Water Transport Engineering (Ministry of Transport) and Taiyuan University of Science and Technology-this standard was released on January 12, 2026, and will come into effect on August 1, 2026; this marks its initial release. These weighing safety protection systems are primarily used on port cranes equipped with grabs, playing a crucial role in both operational volume statistics and safety. This article outlines the key technical requirements of these systems based on the JT/T 1577-2026 standard.
This standard specifies the composition, general requirements, weighing and metrological requirements, and safety protection requirements for weighing safety protection systems on grab cranes. It applies to the design, manufacture, and use of such systems-which utilize continuous analog current and voltage values for measurement data-on cranes that operate using grabs, including general-purpose bridge cranes, general-purpose gantry cranes, bridge-type grab ship unloaders, portal cranes, gantry-mounted cranes, high-tower cranes, and stationary cranes.
Composition of the Weighing Safety Protection System
The weighing safety protection system (hereinafter referred to as the "System") generally consists of current sensors, voltage sensors, a hoisting mechanism electrical weighing processor, a weighing control unit, a display, a transmission module, and a management platform.
General Requirements
1) Operating ambient temperature range: -25°C to +60°C. Maximum relative humidity: ≤95% (condensation and salt spray permissible).
2) System control power supply: AC, rated voltage 220 V ± 10%, frequency 50 Hz. Insulation resistance for AC-powered devices: ≥1 MΩ.
3) System ingress protection (IP) rating: ≥IP44 for indoor use; ≥IP65 for outdoor use.
4) System weighing response time: ≤2 s. 5) Weighing units must be consistent.
5) Required system functions:
a) System self-test routine upon power-up to verify alarm and display functions.
b) Functions for recording, compiling statistics on, and tracing data and fault information collected from the grab crane.
c) Real-time processing and control of data collected from the grab crane.
d) Fault self-diagnosis function; immediate alarm signal generation if a system fault affects normal operation.
e) Desirable functions include ship unloading volume statistics, statistical reporting, maintenance tracking for critical components, and throughput data inquiry.
6) Current sensor measurement error:
≤±1%; voltage sensor measurement error: ≤±0.5%.
7) Real-time calculation of grab crane load weight based on current and voltage; tare function included; real-time transmission of load weight to the weighing control host.
8) Weighing control host:
a) Hardware sampling period during the operating cycle: ≤20 ms.
b) Capability to store crane-collected data and historical records while meeting real-time performance and data integrity requirements.
c) Stored data must include data ID and timestamp (operating time).
d) Capability to transfer/export stored data. e) Data storage unit must retain all collected information during power-off or power interruption.
f) Notification to management for data backup before storage capacity reaches the preset limit.
g) The data storage duration shall be no less than 30 consecutive working days.
h) Protective action commands and alarm signals shall be automatically issued based on the crane's load weight.
9) The display unit shall feature a user-friendly human-machine interface, and text should preferably be displayed in Simplified Chinese.
10) The system shall be equipped with data exchange interfaces for external devices, and communication protocols shall comply with relevant standards such as DP and MODBUS.
Safety Protection Requirements
1) The system shall exchange collected weight data with the grab crane's control system in real time.
2) When the actual load exceeds 95% of the rated lifting capacity, the system shall issue an audible and visual pre-warning signal.
3) When the actual load is between 100% and 110% of the rated lifting capacity, the system shall issue an audible and visual alarm signal and automatically cut off the lifting power source; however, the mechanism shall still be permitted to perform lowering and grab-opening movements.
4) Once triggered, the pre-warning and alarm signals shall remain active throughout the crane's load-handling work cycle until the overload condition is cleared.
5) The audible pre-warning and alarm signals shall differ from each other and be clearly distinguishable from the crane's ambient noise. The visual pre-warning signal shall be yellow, and the visual alarm signal shall be red; both shall be clearly visible within the operator's field of vision. The standard also specifies requirements regarding the system's appearance, access permissions, and other basic aspects; please refer to the original text for further details.
