Forklift charging stations
Forklifts are one of the widespread types of non-road transport in the plant and operate on rechargeable batteries that require periodic charging. The most commonly used acid batteries of types APN-500 and 1SEP-250 and alkaline batteries of type 24TZHN-500, the technical data of which are given in table 1.
table 1
Technical data for domestically produced forklift batteries
battery type Nominal capacity at 8-hour discharge mode, Ah. Number of batteries Nominal voltage Maximum permissible minimum voltage during operation, V Charging current, A Charging time, h Discharge, current, A 15AP11-500 500 15 30 24 70
35
5
10
62 24ТЖН-500 500 24 30 24 125
110
7
8
62 16EP-250 250 16 30 24 80 11 70
Batteries are charged without removing them from forklifts, directly in the depot in the parking lot or with removal from forklifts, in special rooms.
Semiconductor rectifiers are used as chargers. Most often these rectifiers work three-phase bridge circuit full wave rectification.The AC voltage of the rectifiers is 380/220 V, and the DC voltage is 42 V, the rectified current is 70 A, and the efficiency is 0.65.
Batteries are charged using the rectifier-battery method. The connection points are installed at the battery charging points. Special connection points and discharge resistors are required for batteries mounted on a forming or training charge-discharge. The front view of such a point and its diagram are shown in fig. 1.
Rice. 1. Forming point for forklift batteries (charging station): a — facade, b — diagram: 1 — resistance, 2 — DC shield, 3 -shunt.
The choice of discharge resistors is made in such a way that they can serve both for normal (seven-hour) and for forced (three-hour) discharge.
The resistance of the normal discharge section is:
where U is the nominal voltage of the battery, c, Ip is the normal discharge current, a, r is the resistance of the connecting wires, ohms.
When determining the resistance for a three-hour discharge, first find the value of the discharge current:
where Q is the battery capacity in amp hours, t is the discharge time in hours.
Using the same formula, find the total resistance for a three-hour discharge:
The resistance of the second section is determined by the well-known formula:
