High-voltage power-down and voltage check
Pull the low-voltage service disconnect, wait 10 minutes, then prove the part is dead with a CAT III 1000 V meter: HV+ to HV−, HV+ to chassis and HV− to chassis must all read below 60 V. The battery packs themselves stay at about 766 V at all times.
高压下电与验电
拔下低压维修断电插头，等待 10 分钟，再用 CAT III 1000V 万用表验电：高压正-负、正-车架、负-车架三个读数都必须低于 60V 才能动手。电池包本身始终带电，约 766V。
1. Principle1. 原理
Every way of switching the high voltage off on this truck is indirect: it opens contactors. A welded contactor stays closed. That is why a switch-off only means "should be dead", and a measurement is what proves it.
| Method | Type | How it disconnects | When it can fail |
|---|---|---|---|
| Pull the low-voltage service disconnect | Indirect | Contactor coils and the high-voltage interlock lose power; contactors open | A welded contactor does not open |
| Emergency stop, or disconnect the 24 V battery negative | Indirect | Same as above | Same as above |
| Remove a fuse or unplug a high-voltage connector | Direct | Physical break | Requires opening a cover or a connector, so it must be proven dead first |
| Manual service disconnect (MSD) | — | Not fitted on this truck | |
What is still live after power-down
- Inside each battery pack and at its output connectors: always. No power-down step changes this.
- Capacitors in the power distribution unit, motor controllers, DC/DC and inverters hold charge after switch-off. Active discharge brings the motor-controller bus below 60 V within 1 second; if active discharge fails, passive resistors take over. The 10-minute wait covers that worst case.
- Floating (IT) system: neither HV+ nor HV− is connected to the chassis. With damaged insulation one pole can be live to chassis. That is why three readings are taken, not one.
Safe limit: below 60 V DC (the DC limit of UN ECE R100 and GB 18384). After a correct power-down the reading is close to 0 V.
本车所有断开高压的方式都是间接的：靠接触器断开，而接触器触点可能粘连。所以断电只能说明"应该没电了"，必须实测才算确认。
| 方式 | 类型 | 怎么断开 | 什么情况下会失效 |
|---|---|---|---|
| 拔低压维修断电插头 | 间接 | 接触器线圈和高压互锁掉电，接触器弹开 | 接触器触点粘连时断不开 |
| 急停，或断开 24V 蓄电池负极 | 间接 | 同上 | 同上 |
| 拔熔断器或高压插头 | 直接 | 物理断开 | 要先开盖或拆插头，本身必须先验电 |
| 手动维修开关（MSD） | — | 本车没有 | |
下电后哪里仍然带电
- 电池包内部和电池包输出插头：始终带电。任何下电步骤都不会改变这一点。
- 电容：配电盒、电机控制器、DC/DC、逆变器里的电容断电后仍然存电。主动放电 1 秒内把电机控制器母线降到 60V 以下；主动放电失效时由被动放电电阻慢慢放掉。等待 10 分钟就是按这种最坏情况定的。
- 浮地系统（IT 系统）：高压正、负都不接车架。绝缘损坏时，某一极对车架可能带电，所以要测三组读数，而不是一组。
安全电压：直流低于 60V（UN ECE R100 与 GB 18384 的直流限值）。正确下电后读数应接近 0V。
2. Where the high voltage is on this truck2. 本车高压布置
Each battery pack has its own HV+ and HV− connector and its own positive and negative cable to the power distribution unit (PDU). That run has no switch in it and is always live. Only circuits after the PDU contactors go dead on power-down.
每个电池包有自己的 HV+、HV− 插头，各走一根正电缆、一根负电缆到多合一配电盒。这一段中间没有任何开关，永远带电。只有配电盒接触器之后的回路下电后才会没电。
| Version | Pack positions | Cells per pack | Pack voltage, nominal / operating |
|---|---|---|---|
| LFP | 1 left upper · 2 left lower · 3 right upper · 4 right lower | 238 | 766.4 V / 595–868.7 V |
| NCM | 1 left upper · 2 left middle · 3 left lower · 4 right upper · 5 right middle · 6 right lower | 204 | 754.8 V / 571.2–887.4 V |
- Pack end: three connectors on the top edge of each pack: one small low-voltage connector and two round high-voltage connectors (HV+ and HV−). Go by the + / − marking on the connector itself.
- Cables: one positive and one negative cable per pack.
- PDU end: one row of 12 vertical plugs under the PDU, the positive and negative of inputs B1–B6.
| 版本 | 电池包位置 | 每包串数 | 每包额定 / 工作电压 |
|---|---|---|---|
| 磷酸铁锂 LFP | 1 左上 · 2 左下 · 3 右上 · 4 右下 | 238 | 766.4V / 595–868.7V |
| 三元 NCM | 1 左上 · 2 左中 · 3 左下 · 4 右上 · 5 右中 · 6 右下 | 204 | 754.8V / 571.2–887.4V |
- 电池包端：每包顶部边缘 3 个插头：1 个小的低压插头 + 2 个圆形高压插头（HV+、HV−）。以插头实物上的 + / − 标识为准。
- 电缆：每包一根正电缆、一根负电缆。
- 配电盒端：配电盒下方一排 12 个竖直插头，对应 B1–B6 的正和负。
3. Tools and protective equipment3. 工具与防护
Do not start high-voltage work unless every item below is in place.
| Item | Requirement |
|---|---|
| Multimeter | CAT III 1000 V or higher, DC range at least 1000 V, shrouded probes |
| Known voltage source | To prove the meter before and after (the truck's 24 V battery is fine) |
| Insulating gloves | Class 0 (1500 V DC) with leather over-gloves; air-test before use |
| Face shield | Arc-rated |
| Insulated tools | 1000 V rated sockets and torque wrench |
| Lock-out / tag-out | Key and service disconnect kept on the technician; "High-voltage work — do not energise" sign on the truck |
| Second person | Present throughout, with an insulated rescue hook |
| Diagnostic tool | To read fault codes and contactor status before power-down |
下表每一项都到位后才能开始高压作业。
| 项目 | 要求 |
|---|---|
| 万用表 | CAT III 1000V 或更高，直流量程 ≥ 1000V，表笔带护套 |
| 已知电源 | 用于测前、测后验表（车上 24V 蓄电池即可） |
| 绝缘手套 | 0 级（直流 1500V），外套皮革保护手套；使用前充气检漏 |
| 面罩 | 防电弧 |
| 绝缘工具 | 1000V 绝缘套筒和扭力扳手 |
| 上锁挂牌 | 钥匙和维修断电插头由作业人员随身保管；车上挂"高压作业 禁止上电"牌 |
| 监护人 | 全程在场，备绝缘救援钩 |
| 诊断仪 | 下电前读故障码和接触器状态 |
4. Power-down procedure4. 下电流程
- Park. Stop the truck and apply the electronic parking brake. Make sure no charging cable is connected.
- Read fault codes. Connect the diagnostic tool and read the PDU fault codes. If any contactor-welded fault is present (main drive, auxiliary, heater, body-builder or fast-charge contactor), stop and go to section 6.
- Pull the low-voltage service disconnect. Either location; the truck then cuts the high voltage automatically.
- In the cab: behind the trim cover at the lower left of the dashboard.
- Outside: open the door, open the front flip cover, then in the compartment.
- Lock out and tag out. Keep the disconnect plug and the key on you. Hang the "do not energise" sign.
- Disconnect the 24 V battery negative. High voltage is powered down first, then the battery negative.
- Wait at least 10 minutes from step 3, for the capacitors in the motor controllers and other high-voltage loads to discharge.
- Put on protective equipment. Insulating gloves with over-gloves and face shield. Second person in position.
- Prove dead. Measure at the part you will work on, as in section 5. Start work only when all three readings are below 60 V.
To restore: refit every high-voltage connector until it clicks and tug it once, refit the service disconnect, reconnect the battery negative, power up and read fault codes to confirm no insulation or interlock fault.
- 停车。停稳车辆，开启 EPB 电子驻车制动；确认充电枪已拔下。
- 读故障码。连接诊断仪，读取配电盒故障码。如有任何接触器粘连故障（主驱、辅驱、加热、上装或快充接触器），停止并转第 6 节。
- 拔下低压维修断电插头。两处任选一处，拔下后车辆自动解除高压：
- 车内：仪表台左下方装饰盖板内。
- 车外：打开车门 → 打开前翻转盖板 → 机舱内。
- 上锁挂牌。断电插头和钥匙随身携带，车上挂"禁止上电"牌。
- 断开 24V 蓄电池负极。先下高压，再断负极。
- 等待至少 10 分钟（从第 3 步开始计时），让电机控制器和其他高压负载的电容放完电。
- 穿戴防护。绝缘手套加外层手套、面罩；监护人就位。
- 验电。按第 5 节在要作业的部件上测量，三个读数都低于 60V 才能开始作业。
恢复：装回所有高压插头（插到听见"咔嗒"再拉一下确认）→ 装回维修断电插头 → 连接蓄电池负极 → 上电后读故障码，确认没有绝缘和互锁故障。
5. Prove dead: where to measure and what to expect5. 验电：测哪里、应该看到多少
Measure at the high-voltage connector of the part you will work on (zone B), in this order. It is called live–dead–live: the meter is proven before and after, so a zero reading can be trusted.
| Step | Measure | Expected | If not |
|---|---|---|---|
| ① Prove meter | 24 V battery terminals | 24–28 V | Meter or probes faulty: replace |
| ② HV+ to HV− | At the connector of the part | below 60 V (≈ 0 V) | Contactor still closed or capacitors not discharged: stop, section 6 |
| ③ HV+ to chassis | HV+ to a chassis ground point | below 60 V | Insulation fault or one contactor welded: stop |
| ④ HV− to chassis | HV− to a chassis ground point | below 60 V | Same as ③ |
| ⑤ Prove meter again | Back on the 24 V battery | 24–28 V | Meter failed during the test: earlier zeros are void, repeat with another meter |
Readings in zone A are different
| Point | Normal reading | Meaning |
|---|---|---|
| Pack HV+ to HV− (pack socket, cable removed) | LFP 595–868.7 V · NCM 571.2–887.4 V | Normal. The pack is always live. Measure only for diagnosis. |
| Pack HV+ or HV− to chassis | Near 0 V, or drifting unsteadily | Normal for a floating system. A steady reading near pack voltage means an insulation fault. |
Why three readings: the system floats. With one contactor open, the other welded and the insulation damaged, HV+ to HV− can read 0 V while one pole sits several hundred volts above the chassis.
在要作业部件的高压插头上测量（B 区），按下面顺序。这叫"测-验-测"：测量前后都验表，读到的 0V 才可信。
| 步骤 | 测什么 | 应该看到 | 不对说明 |
|---|---|---|---|
| ① 验表 | 24V 蓄电池正负极 | 24–28V | 表或表笔坏了，换表 |
| ② 正 ↔ 负 | 部件插头的 HV+ 与 HV− | 低于 60V（≈ 0V） | 接触器没断开或电容没放完：停止，转第 6 节 |
| ③ 正 ↔ 车架 | HV+ 与车架搭铁点 | 低于 60V | 绝缘损坏或一侧接触器粘连：停止 |
| ④ 负 ↔ 车架 | HV− 与车架搭铁点 | 低于 60V | 同 ③ |
| ⑤ 再验表 | 回到 24V 蓄电池 | 24–28V | 表在测量中坏了，之前的 0V 作废，换表重测 |
A 区的读数和 B 区不同
| 测量点 | 正常读数 | 解读 |
|---|---|---|
| 电池包 HV+ ↔ HV−（拔下电缆后的包端插座） | LFP 595–868.7V · NCM 571.2–887.4V | 正常，电池包永远带电。只在诊断时测。 |
| 电池包 HV+ 或 HV− ↔ 车架 | 接近 0V，或读数漂移不稳 | 浮地系统的正常现象。稳定在接近包电压说明绝缘有故障。 |
为什么测三组：系统是浮地的。一极接触器已断开、另一极粘连、再加上绝缘损坏时，正-负可能读到 0V，而某一极对车架却有几百伏。
6. If something is wrong6. 异常处理
In every case below: stop work and step away from live parts first.
| Situation | Action |
|---|---|
| HV+ to HV− still above 60 V after 10 minutes | Wait another 10 minutes and measure again. If it does not fall, a contactor has not opened: treat as welded. |
| Contactor-welded fault code, or HV+ to HV− steady at pack voltage | That circuit is still connected to the battery. Do not unplug under load (it will arc). Escalate to a qualified high-voltage specialist. |
| One pole steady at several hundred volts to chassis | Insulation fault. Any metal on the truck may be live. Close off the area and escalate. |
| Meter check ① or ⑤ fails | Change meter and restart at ①. Earlier readings are void. |
| Battery pack impacted, flooded, smoking, smelling or hot | No voltage check, no pack work. Move the truck to an open area, isolate it and monitor temperature. Stop any charging. |
| Damaged high-voltage cable | Wrap the damage with insulating tape, then prove dead. |
Never open a battery pack housing. Even after power-down, do not touch battery pack components.
以下任何情况：先停止作业，人离开带电部位。
| 情况 | 处理 |
|---|---|
| 等够 10 分钟后，正-负仍高于 60V | 再等 10 分钟复测；仍不下降，说明有接触器没断开，按粘连处理 |
| 有接触器粘连故障码，或正-负稳定在电池电压 | 该回路仍连着电池。不得带电拔插头（会拉弧）。交由有资质的高压专业人员处理 |
| 某一极对车架稳定在几百伏 | 绝缘故障，车上任何金属都可能带电。封闭区域并上报 |
| 验表 ① 或 ⑤ 失败 | 换表从 ① 重新开始，之前读数作废 |
| 电池包受撞击、泡水、冒烟、有异味或温度异常 | 不验电、不动电池包。车辆移到开阔处隔离，监测温度；停止充电 |
| 高压线束破损 | 用绝缘胶带缠住破损处，再验电 |
任何情况下都不得打开电池包壳体。即使已经下电，也不要触碰电池包部件。
Based on the Windrose service manual, section 1.9 (high-voltage power-down) and chapter 4 (new-energy components). Applies to all markets.依据苇渡维修手册第 1.9 节（高压系统下电）和第 4 章（新能源部件）。适用于所有市场。